Having come to Canada upon hearing the fake news that his mother Haruko is in critical condition, high school student Kaidou Haru meets a young boy named Ren. Haru is forced to spend the summer with Ren. Every day is a battle.

It's been five years since that summer. Haru works as a host while saving money for his twin brothers' tuition. One day, Haru's lawyer Mikiko invites him to her office where he is reunited with Ren.

Brothers Aki and Shima are upset by the sudden appearance of a "fourth brother" in the Kaidou family, and Haru's excessively affectionate attitude towards Ren makes Aki explode with rage. Meanwhile, Haru happens to witness a car accident in the city.

Spring arrives, and Haru's dream of living with his brothers finally comes true. They move into a house together, and with the help of his former coworker Ikuyoshi, Haru's plans to open a cafe seem to be coming along as well.

Just when Ren begins attending school, he's seen kissing Haru goodbye by his classmate who is curious about their relationship.

While Haru and Ren are out at a nearby zoo, Aki calls Haru to let him know a woman calling herself "Kiyoka" has showed up at the house. Kiyoka is Haru's high school classmate and the co-owner of the cafe they're about to open.

Ren manages his school life with the help of his classmates, but he collapses during a PE class.

Haru's cafe "WHITE FANG" begins flourishing immediately after it opens. Even Haru and Ren's recently awkward relationship is getting back to normal. However, Aki is in a terrible mood.

Haru suddenly awakens to the sound of rain in his room. Shaken by the sight of Ren in his dream, his breathing becomes erratic. Realizing the reason for his dream, the next morning Haru questions Ikuyoshi.

The e-mail Ren sent prompts Haruko to come to Japan all the way from Switzerland. Eagerly looking forward to seeing Haruko again, Ren innocently bubbles with excitement. What will happen to the brothers' quiet life?!

It's been three months since Haru's dream to live under the same roof with all three of his brothers came true. However, the situation at the Kaidou household suddenly becomes stormy when Haruko announces she's taking Ren back to Switzerland with her. Even after Ren hears about Haruko's secret loneliness from Miki, he still wishes to stay in Japan as long as Haru wants him. But unable to express his desire in words, Ren continues to remain "just a brother" to Haru...

Because their mother Haruko is staying with them, Haru continues to watch his public displays of affection with Ren. Without much consideration for his situation, Ikuyoshi asks Haru a question. Meanwhile, unable to express his feelings for Haru, Ren and his classmate Juuzen question their school's doctor Takamura. One day, after hearing about Haru's medical checkup after the accident, Aki aggressively attacks Haruko...

It's Ren's first summer vacation in Japan. The landlord of the apartment he and Haru once lived in hires him to clean one of his apartment units. Haru becomes unbearably curious when Ren refuses to tell him why he got a part time job. Kiyoka suspects Kiri, Ren's female classmate who has been coming over with her dog to hang out. Meanwhile, an unknown man approaches Ren.

Ren is forced into the car of a strange man. Natsuki, who bears a striking resemblance to Haru, claims to be the cousin of the Kaidou brothers. Shiba Natsuo tells Ren to keep it a secret from his brothers that they met, but Ren is met by Haru and the twins who were concerned that he was so late coming home. Haru tells Ren to quit his job out of concern, but Ren is sick of being treated like a child.

Ren spends the night away from home and brings home a large amount of money. Haru, who was up all night with worry, begins acting cold towards Ren when he won't tell him why. The next morning, Ren heads out to his friend Kiri's house to train her family's dog without clearing the air between them. In order to avoid being at cross-purposes with each other, Haru goes to buy a new phone for Ren. A strange man calls Ren's cell phone.

The accident that made Haru lose his parents seven years ago left him on the brink of death. Though he made a miraculous recovery, he hasn't gone to the hospital for a checkup since he was released, so a concerned Aki and Shima ask Ren to take him there. Unaware of the situation, Haru believes Ren is taking him on a date, but they end up at the hospital. While waiting for Haru in the waiting area Haru's psychotherapist Mori strikes up a conversation with Ren.

A new tenant is moving into Onodera's aparment where Haru and Ren used to live, and Ren is helping to clean the room. The man who appears with Onodera is Takamura, the school nurse at Ren's high school. Meanwhile, a female customer begins showing up at cafe WHITE FANG practically every day to talk to Haru. Aki and Shima realize she's the girl from the marriage meeting photo.

Unable to stand being treated by a child by Haru, Ren leaves the house. Natsuo agrees to let Ren stay over when he suddenly shows up at his apartment, but Haru shows up just as he's about to grant Ren's request to do something that he "can't tell Haru about." Haru tells Ren to not come home ever again.

Since Haru told Ren to stay away from Natsuo the relationship between Haru and Ren has become awkward, though on the surface their life appears normal. Ren's strangely obedient and quiet behavior reminds Haru of the time two years ago when he returned to Canada alone and it makes him uneasy.

Since Haru declared that he belongs to Ren, Ren has stopped making unreasonable requests. Though plenty of women still come to the cafe, Haru has begun flatly rejecting them, and their days are peaceful. Meanwhile, Natsuo is experiencing emotions he can't express in words. His irration with the former number one host "Natsu," and his childhood memories of Haru. As this is happening, he hears the Kaidou family has decided to hold a birthday party for Aki and Shim.