1 (53)- "Wakare no Asa" ("Morning of Separation")(別れの朝)
Airdate: April 3, 2004
Kaito flies to Hawaii after spending a night with Lucia and saying goodbye to her, and she meets Rihito Amagi who seems fond of her. Taro Mitsuki announces his plans of heading to Germany, leaving Hanon disappointed. Luchia sees the image of a young mermaid in her dreams. Luchia, Hanon, and Rina face a new foe, Michel a powerful angel.
2 (54)- "Suiheisen no Kanata" ("That Horizon")(水平線の彼方)
Airdate: April 10, 2004
Luchia gets a phone call saying that Kaito was lost at sea and sets out to the open sea to search for him. Luchia learns the mermaid in her dreams is Sara's successor - Seira.
3 (55)- "Mizuiro no Merodī" ("Aquamarine Melody")(水色の旋律(メロディー))
Airdate: April 17, 2004
Hanon wants to say good bye to Taro-chan, but she gets stalled. She reaches him at last and gets a present from him, a music sheet written just for her. However, after Taro-chan's flight takes off, the music sheet blows away, leaving Hanon upset and a mysterious person to retrieve it...
4 (56)- "Shiawase no Yokan" ("A Premonition of Happiness")(幸せの予感)
Airdate: April 24, 2004
Rina gets a letter from her whale friend, saying she should go home. She also meets a flirty boy named Masahiro Hamasaki, whom she keeps on meeting. Rina changes her mind about the offer to return home at the last second.
5 (57)- "Maesutoro" ("Maestro")(マエストロ)
Airdate: May 1, 2004
Hanon and Luchia go to a concert, where Rihito conducts an orchestra.
6 (58)- "Toshishita no Otoko no Ko" ("The Young Man")(年下の男の子) May 8, 2004
Kaito has finally returned, but he has lost his memories of Lucia, and everything that involves the ocean! Hanon has also found herself a suitor, Nagisa Shirai, seen to be the retriever of the music sheet Taro-chan gave her. To make things worse for Lucia, Kaito is with another girl, named Michal who is Rihito's sister, and Lucia falls into deep depression and vows she will restore Kaito's memories.
7 (59)- "Ubawareta Kokoro" ("Her Stolen Heart")(奪われた心)
Airdate: May 15, 2004
Luchia pinpoints the location of Seira's spirit in India. But before Seira's spirit merges with the orange pearl, Michel absorbs Seira within himself. Lucia must now collect the falling heart fragments of Seira, in order for her to be brought back to life.
8 (60)- "Kioku no Hate" ("The End of the Memories")(記憶の果て)
Airdate: May 22, 2004
In an effort to have Kaito's memories returned, Luchia, Hanon, Rina, and some of Kaito's friends let him take up surfing lessons again. Luchia appears as a mermaid to Kaito to help him remember at least.
9 (61)- "Koi no Echūdo" ("Love Etude")(恋の練習曲(エチュード))
Airdate: May 29, 2004
Hanon decides to play the sheet music Taro Mitsuki gives her. She however can't play the piano, so Nagisa buys her a piano book to help her, only to have Kaito help her instead. This episode introduces Lady Bat, a new villain, and Hanon's new image song, Mizuiro no Senritsu.
10 (62)- "Nokoru Omoi" ("Leftover Feelings")(残る想い)
Airdate: June 5, 2004
Rina returns to her country in the North Atlantic Ocean to attend a ceremony there. But she also starts to miss Masahiro and ends up missing something very important from him.
11 (63)- "Aniki no Kimochi" ("Her Brother's Feelings")(兄の気持ち)
Airdate: June 12, 2004
Luchia, Hanon, and Rina hang out with Kaito and Michal around town by shopping.
12 (64)- "Hikari no Umi no Māmeido" ("The Marine Mermaid's Light")(光の海の人魚(マーメイド))
Airdate: June 19, 2004
Coco invites Luchia, Hanon, and Rina to come with her to the Indian Ocean to help search for the Legendary Spiral Shell. It turns out to be Sara's shell that held all of her memories, and the four (also Hippo) battle the Black Beauty Sisters for it.
13 (65)- "Kare no Himitsu" ("His Secret")(カレの秘密)
Airdate: June 26, 2004
Hanon and Rina are at an ice cream parlour eating ice cream. Rina meets Masahiro there. Nagisa also meets Masahiro after misjudging that he was flirting with Hanon. The next day, Hanon shows Rina a magazine with a picture of Masahiro and his rich father. Rina then wants to know more about Masahiro at that point. However, she gets upset when Masahiro refused to tell her the truth on why he likes motorcycling and boxing. He sends her tickets to go to his boxing match, which she turned down the offer, and Masahiro loses to a world champion.
14 (66)- "Yami Kara no Koe" ("Voice From the Dark")(闇からの声)
Airdate: July 3, 2004
Rina notice Kaito is paying more attention to Luchia, then she offers him a trip to the cave with lighted candles, and he remembers something. This episode introduces Lanhua, a new villain. Gaito's spirit appears before Kaito reminding him who is his most important person. Aqua Regina appears and gives the Mermaid Princesses a new song.
15 (67)- "Nanatsu no Umi no Inori" ("Prayer of the Seven Seas")(七つの海の祈り)
Airdate: July 10, 2004
Luchia, Hanon, and Rina head for Antarctica after recent events there worry Caren. Something is causing an enormous iceberg to melt, which can create a tsunami across the whole globe. The mermaid princesses must use all their strength to prevent global disaster by Michel. Also, Caren finds love, Subaru.
16 (68)- "Natsu Yasumi Da Yo! Zen-in Shūgō" ("It's Summer Vacation! Let's Gather, Everybody!")(夏休みだヨ!全員集合)
Airdate: July 17, 2004
In order for Maki's beach house to compete with a nearby hotel, Luchia, Hanon, and Rina hire Karen, Noel, and Coco to help them in their chores. The six Mermaid Princesses engage in a beach volleyball match against some guests of the hotel. (Only considered non-filler due to the introduction of the secondary trio and the establishment of their new role.)
17 (69)- "Manatsu no Serebu na Yoru" ("A Midsummer Night's Celebration")(真夏のセレブな夜)
Airdate: July 24, 2004
Nagisa obtains a pair of celebration tickets from Masahiro and decides to take Hanon out. But his plans to have Hanon's consent end up with him being played around by Coco, Noel, and Karen in order for Hanon to realize her true feelings for Nagisa. This takes a turn when Hanon gets jealous. When Nagisa is about to take Hanon to the celebration, he realizes that he lost the tickets, upsetting Hanon. He then decides to take her by boat to a view where the celebration takes place.
18 (70)- "Hoshi no Rabirinsu" ("Star Labyrinth")(星の迷宮(ラビリンス))
Airdate: July 31, 2004
The six Mermaid Princesses find themselves in a magical world as a mysterious event grants two wishes at the same time. Hippo has a brief reunion with his beloved Yuri, and Seira enjoys a one day fun with Luchia.
19 (71)- "Iyashi no Uta" ("Song of Healing")(癒しの歌)
Airdate: August 7, 2004
The King of the Squids, Somegorō, asks the Mermaid Princesses for help as his people are being terrorized by the Black Beauty Sisters.
20 (72)- "Koi no Tentei" ("Love Detectives")(恋の探偵)
Airdate: August 14, 2004
To find out why Masahiro likes Rina so much, Karen dates with him while Coco and Noel watch from the sidelines, keeping Luchia and Hanon out of the fray.
21 (73)- "Koi no Fuhōshinnyū" ("Love Intrusion")(恋の不法侵入)
Airdate: August 21, 2004
Luchia found her keys to Kaito's house and remembers the promise to keep his house clean while he was gone. When she is cleaning the bathroom, Luchia accidentally gets wet and decides to take a bath. Meanwhile, Kaito realizes that someone is in his house... Also, Alala gets introduced in this episode.
22 (74)- "Omoi de Dorobō" ("Robber of Memories")(思い出泥棒)
Airdate: August 28, 2004
Coco, Noel, and Karen leave. Luchia then gets a strange box from Rihito. Later, Luchia, Hanon, Rina believe that there is a robber at Pearl Piari when there is a mess in the kitchen, so they decide to set up traps, unintentionally catching Nagisa and finding out the thief was a cat; the box gets stolen however and Luchia looks all over town for it. In the end, it turns out that Rihito himself stole the box.
23 (75)- "Kokoro no Oku no Kokoro" ("Feelings Inside")(心の奥のこころ)
Airdate: September 4, 2004
Luchia, Hanon, and Rina are invited to a concert wherein Rihito conducts an orchestra. During the performance, Rihito's power is suddenly revealed. Meanwhile, the all of Michel's minions are given a new power made from a part of Seira's heart. All five surround the concert hall, singing, causing the concert hall to begin crumbling, after which Rihito stops using his power to keep the building together. Lady Bat, Lanhua, and Alala leave when it seems like the plan failed. The Black Beauty Sisters use their new power to create a new "dimension" and "clones" to sing another song. Suddenly, Aqua Regina appears and gives the mermaids a new song.
24 (76)- "Watashi no Hoshii Mono" ("I Wish...")(私の欲しいもの)
Airdate: September 11, 2004
To cheer up a crying Luchia, Hanon and Rina take her to a karaoke joint, which just happens to have their songs. They sing and get horrible scores on their own songs! Being angered by that, the three transform into their idol forms and sing, causing Lanhua (who was the cause of everything) to go capture them. Rihito gives Luchia a ride to a nice scenery, he offers her a gift, but is surprise to hear that the only thing she wants is Kaito.
25 (77)- "Koi Uranai" ("Love Fortune")(恋占い)
Airdate: September 17, 2004
Hanon tries to cheer Luchia up by bringing her to a fortune teller. The fortune teller tells Luchia to throw her most precious item in the sea (which is her ring). Luchia does so, but then the next day, it turns out that the fortune teller is a fake. Luchia goes into the sea to retrieve her ring. She is almost captured by Lady Bat (who was the fortune teller) before Hanon and Rina arrive.
26 (78)- "Aidoru Debyū" ("Idol Debut")(アイドルデビュー)
Airdate: September 24, 2004
A man goes around looking for people to be idols. He asks Alala (who is in human form and accepts) and Rina. Rina (who is with Masahiro at the time) looks at the poster, before Masahiro grabs it out of her hands and rejects. When Masahiro sees Rina staring at a poster of Alala, who became a new idol, he thinks he ruined her dream of becoming an idol. The three mermaids end up at the concert and defeat Alala.
27 (79)- "Ketsuretsu no Shisutāzu" ("Separated Sisters")(決裂の姉妹(シスターズ))
Airdate: October 2, 2004
After another loss at the hands of the Three Mermaid Princesses, the Black Beauty Sisters bicker at each other because of Fuku's comments. Mimi leaves Sheshe during their argument because Sheshe keeps on blaming their losses on her. Mimi tries to capture the mermaid princesses on her own, and fails, almost dying. Sheshe uses the new power given to them by Michel to heal Mimi, as she doesn't care if they get "kicked out" or not; she would rather die in the sea with her sister.
28 (80)- "Seira no Hanazono" ("Seira's Flower Garden")(星羅の花園)
Airdate: October 9, 2004
Luchia's class takes a trip to a greenhouse, and she starts to brighten as Kaito sits beside her, much to Michal's dismay. Seira's spirit alerts Luchia, Hanon, and Rina of an impending danger. Kaito remembers Luchia's birthday from before.
29 (81)- "Mitsukai-tachi no Yūutsu" ("Gloom by a Triple-Threat")(みつかいたちのゆううつ)
Airdate: October 16, 2004
The Black Beauty Sisters, Lady Bat, Lanhua, and Alala hatch up plans to capture Hippo and use him as bait for the Mermaid Princesses.
30 (82)- "Dakishimete..." ("Embrace Me...")(抱きしめて...)
Airdate: October 23, 2004
Rina still cannot confess her feelings to Masahiro because of her identity, however Rina learns how strong her feelings are for Masahiro. In the end, Masahiro swears he won't let Rina go no matter what, and the two finally confess their feelings and shared a kiss.
31 (83)- "Saigo no Rabu Retā" ("The Last Love Letter")(最後の恋文(ラブレター))
Airdate: October 30, 2004
Hanon begins to meet Nagisa more. But her feelings have become torn as she receives a letter from Taro Mitsuki, her former music teacher. Nagisa discovers this and invites Hanon to hang out with him the next day. However, things take a turn when Lady Bat shows up at the place Hanon and Nagisa end up going to. Hanon chose to stay with Nagisa.
32 (84)- "Umi ni Kiete Kioku" ("Memories Vanished At Sea")(海に消えた記憶)
Airdate: November 6, 2004
Luchia is slowly convinced that Kaito's memories have fully returned, as he experience his time surfing. But Michel tries to make sure Kaito's previously lost memories remain lost. Kaito remembers what really happened back in Hawaii, and vows to protect Luchia.
33 (85)- "Madareru Kokoro" ("Confused Heart")(乱れる心)
Airdate: November 13, 2004
Luchia cherishes her reunion with Kaito. Meanwhile, Mimi becomes torn between duty and friendship as she slowly discovers her enemies' human identities.
34 (86)- "Shiroi Hane no Yūwaku" ("Temptations of a White Feather")(白い羽根の誘惑)
Airdate: November 20, 2004
Michal becomes hysterical as Kaito leaves her for Luchia. A mysterious voice urges Michal to follow it.
35 (87)- "Sayonara no Kawari ni..." ("Instead of a Goodbye...")(さよならのかわりに...)
Airdate: November 27, 2004
Michal decides to "end her pain and sadness" by becoming one with Michel. Luchia, Hanon, Rina, and Kaito go to stop her, but they arrive too late. Lady Bat, Lanhua, and Alala team up to stop the mermaids, if only for a moment, but Aqua Regina appears and gives the trio a new song. The connection between Michal and Michel is revealed.
36 (88)- "Setsubō no Hate" ("The End of Despair")(絶望の果て)
Airdate: December 4, 2004
Michel takes the three mermaids into his dimension and begins to fight them. Seira stops him with a song. Michel absorbs Lady Bat, Lanhua, and Alala. But not before that moment, the three villains reveal that Michel is just like them.
37 (89)- "Tenkū no Shiro e..." ("To the Castle in the Sky...")(天空の城へ...)
Airdate: December 11, 2004
Without any villain attacks for a while, Luchia, Hanon, and Rina spend more time with their boyfriends as their relationships start to grow further. Karen, Noel, and Coco return. Meanwhile, Michel is told that his true self is a fossilize statue, reborn by "The Great One" and guided by Fuku. The six mermaids make their resolve to save Seira from Michel, but they are overpowered. Seira asks Luchia to break the statue that is Michel's true self. Kaito discovers Rihito is a descendant of the Pantharassa like himself.
38 (90)- "Seiya no Tatakai" ("Battle on Christmas Eve")(聖夜の戦い)
Airdate: December 18, 2004
The six Mermaid Princesses, together with Rihito and Kaito, engage on a final battle with Michel. Seira is finally born, ready to fight with her voice. The Great One turns out to be Rihito and Michal's father; everything is explained, and Great One destroys the statue that is Michel's true self. After that, Fuku reveals that he was created to control Michel, should anything go wrong; he does so, but the mermaids still sing a powerful song to defeat him. Aqua Regina makes an appearance and their song gets through to Michel and Michal. The spirits of the original angels appear and invite Michel and Fuku to join them, which they happily accept. In the end, Aqua Regina gives a reborn Michal to Rihito.
39 (91)- "Yume no Sono Saki e" ("Onward to That Dream")(夢のその先へ)
Airdate: December 25, 2004
With all things troubling themselves and the marine world out of the way, the seven Mermaid Princesses celebrate the newfound peace by organizing a little concert—one that becomes a huge reunion of characters from the entire series. Luchia and Kaito share their lovely time together once more in the end.