Character Relationship Map: Rainbow Days

Characters

• Natsuki Hashiba (played by Reo Sano) — protagonist

  A pure-hearted high school student and one of four close friends, Natsuki falls for Anna after she lends him a hand towel. He works up the courage to ask her out, grows closer to her over the school y...

• Tomoya Matsunaga (played by Taishi Nakagawa) — supporting

  A ladies' man and one of Natsuki's three best friends, Tomoya becomes concerned when Mari fears he will take Anna away from her. He distracts Mari so Natsuki and Anna can spend time together, then inv...

• Tsuyoshi Naoe (played by Mahiro Takasugi) — supporting

  An otaku and one of Natsuki's close friends, Tsuyoshi is dating Yukiko. He helps the boys study for their remedial exams, but his plan to apply to a university in Tokyo leaves him conflicted about his...

• Keiichi Katakura (played by Ryusei Yokohama) — supporting

  A sadistic member of Natsuki's close-knit group of friends, Keiichi helps shape events around Anna and Natsuki. He pretends to be Anna's boyfriend to protect her from unwanted advances. Later, he clai...

• Mari Tsutsui (played by Yuri Tsunematsu) — supporting

  Anna's protective best friend, Mari intercepts Natsuki when he tries to return Anna's hand towel and is angry when he gets Anna's Line ID. She worries that Tomoya will take Anna away from her, and lat...

• Anna Kobayakawa (played by Ai Yoshikawa) — supporting

  A high school student who first draws Natsuki's attention by lending him her hand towel after he falls into a puddle. She gradually grows closer to him, though she becomes confused when she sees him w...

• Yukiko Asai (played by Mayu Hotta) — supporting

  Tsuyoshi's girlfriend, Yukiko joins the boys in helping Natsuki, Tomoya, and Keiichi prepare for their remedial exams. She later discovers that Tsuyoshi plans to apply to a university in Tokyo, which...

Canonical Relationships

Family, romantic, and professional connections based on plot evidence.

• Tsuyoshi Naoe → Yukiko Asai (Romantic Girlfriend) — Their established relationship is tested by Tsuyoshi's university plans.

  The plot identifies Yukiko as Tsuyoshi's girlfriend. Their relationship becomes strained when Tsuyoshi considers applying to a university in Tokyo.

• Tomoya Matsunaga → Mari Tsutsui (Romantic Interest) — Tomoya's feelings gradually become sincere and romantic.

  Tomoya invites Mari to the Christmas party, kisses her when she confesses her insecurity, and later admits that he has fallen in love with her.

• Natsuki Hashiba → Anna Kobayakawa (Romantic Love Interest) — Their relationship develops from an awkward school crush into mutual love.

  Natsuki becomes interested in Anna after she lends him her hand towel. They later confess their love to each other and kiss in the planetarium exhibit...

Story Dynamics

Alliances, conflicts, and narrative interactions that evolve throughout the story.

• Keiichi Katakura → Anna Kobayakawa (Alliance Protective Friend) — Keiichi provides direct social protection for Anna.

  When another boy makes unwanted advances toward Anna, Keiichi pretends to be her boyfriend to protect her.

• Mari Tsutsui → Natsuki Hashiba (Conflict Protective Rival) — Mari initially treats Natsuki as a threat to Anna's friendship and safety.

  Mari intercepts Natsuki when he tries to return Anna's hand towel and becomes angry when he obtains Anna's Line ID.

• Anna Kobayakawa → Mari Tsutsui (Social Best Friends) — Their close friendship is challenged by Mari's insecurity and Anna's changing relationships.

  Mari is described as Anna's protective best friend. Mari later says she fears she is no longer Anna's closest friend.

• Tsuyoshi Naoe → Keiichi Katakura (Social Best Friend) — Tsuyoshi acts as a responsible friend within the group.

  Tsuyoshi and Keiichi are members of the four best friends. Tsuyoshi warns Natsuki that Keiichi intends to confess to Anna.

• Tomoya Matsunaga → Keiichi Katakura (Conflict Friend And Rival) — Their friendship is temporarily disrupted by Keiichi's apparent romantic challenge.

  Tomoya gets into a fight with Keiichi after Keiichi says he will pursue Anna if Natsuki does not.

• Tomoya Matsunaga → Tsuyoshi Naoe (Social Best Friend) — They rely on one another within the friend group.

  Tomoya and Tsuyoshi belong to the four best friends. Tomoya seeks academic help from Tsuyoshi and Yukiko after failing his exams.

• Natsuki Hashiba → Keiichi Katakura (Social Best Friend) — Their friendship survives teasing, competition, and Keiichi's deceptive intervention.

  Natsuki and Keiichi are introduced as members of the same group of four best friends. Keiichi later creates an opportunity for Natsuki and Anna to tal...

• Natsuki Hashiba → Tsuyoshi Naoe (Social Best Friend) — Their friendship includes practical academic support.

  Natsuki and Tsuyoshi are part of the four best friends. Natsuki seeks help from Tsuyoshi after failing his exams.

• Natsuki Hashiba → Tomoya Matsunaga (Social Best Friend) — They share a close friendship and support each other's romantic situations.

  Natsuki and Tomoya are introduced as two of four best friends. Tomoya helps distract Mari so Natsuki can spend time with Anna.

Story Analysis

Four friends navigate romance, insecurity, academic choices, and graduation across their final school years.

Plot Progression

1. A Towel Starts Everything — Natsuki meets Anna after falling into a puddle, but Mari immediately becomes protective. The boys turn Natsuki's romantic uncertainty into a bet.
2. Summer Tests and Bonds — The boys fail their exams and depend on Tsuyoshi and Yukiko for help. The summer festival brings the group closer while exposing Mari's fear of losing Anna.
3. Choices and Misunderstandings — Tsuyoshi struggles with university decisions, while Anna becomes confused by Natsuki's closeness to another classmate. Keiichi protects Anna by pretending to be her boyfriend.
4. Winter Confessions — Mari runs away after misreading the birthday surprise, leading to emotional confessions and accidental kisses. Tomoya then openly proves that his love for Mari is genuine.
5. The Rainbow After Rain — Anna misinterprets Natsuki's rehearsal and withdraws from him. Keiichi's final deception gives Natsuki and Anna the chance to confess their love before the rainbow and graduation.