Yoshino Koiwai
Yoshino Koiwai |
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| Kanji: | 小岩井 吉乃 |
| Romaji | Koiwai Yoshino |
| Statistics | |
| Age: | 16-17 |
| Birthday: | November 22nd |
| Height: | 148 cm (4’10”) |
| Portrayed by: | |
| Japanese: | Inori Minase |
| English: | Monica Rial |
Yoshino Koiwai (小岩井 吉乃, Koiwai Yoshino), is one of the main characters in the anime and manga series Masamune-kun no Revenge. She is the personal maid and close aide of Aki Adagaki, the series’ main heroine, and plays a deceptively important role in the progression of the story. Though she initially appears to be a quiet and obedient servant, Yoshino hides a cunning and mischievous nature beneath her polite exterior.
As the story unfolds, Yoshino becomes a central figure in the plot’s intrigue and deception, playing multiple sides while gradually revealing her own motivations. Her role is pivotal in the romantic and emotional conflicts that define Masamune-kun no Revenge.
Background

Appearance in Anime
Yoshino Koiwai has served as Aki Adagaki’s maid since they were children, attending the same school and assisting with Aki’s day-to-day activities. Outwardly reserved and dutiful, Yoshino is often seen silently following Aki, holding umbrellas, or delivering messages. However, unbeknownst to most characters, she is the one who delivered the infamous rejection letter to Masamune Makabe in their childhood, believing she was protecting Aki.
This act, combined with Aki’s nickname of “Pig’s Foot” for Masamune, served as the foundation for Masamune’s quest for revenge. Yoshino later learns of Masamune’s plan and offers to assist him in his revenge though her own reasons remain mysterious and self-serving.
Appearance
Yoshino has a petite frame, long black hair usually styled in low twin braids, and quiet, observant eyes. She often wears her maid uniform, complete with an apron and frilly headband, emphasizing her role as Aki’s personal assistant. Her expressions are generally neutral, but she’s capable of sudden, sharp shifts revealing her manipulative and calculating side when least expected.
Despite her modest presentation, Yoshino is often the most perceptive person in the room, watching others silently while subtly steering events behind the scenes.
Personality
Yoshino is outwardly polite, submissive, and diligent, fitting the image of the perfect maid. However, she is actually intelligent, shrewd, and sly, often using her innocent appearance to manipulate others. She enjoys observing the chaos she helps cause, and her involvement in Masamune and Aki’s lives is far more active and deliberate than she initially lets on.
Though cunning, Yoshino is not heartless. As the series progresses, her internal conflict becomes apparent particularly her guilt over past actions and her growing concern for both Aki and Masamune. Her manipulations are not always malicious, and she eventually develops genuine feelings of regret, friendship, and even affection.
Role in the Story
The Letter and the Lie: Yoshino is the true author of the letter that traumatized Masamune as a child, pretending it came from Aki. This secret drives much of the series’ conflict, as Masamune pursues revenge against Aki, unaware of Yoshino’s involvement.
Assisting Masamune: Yoshino offers to help Masamune with his revenge, feeding him information and creating opportunities for him to get closer to Aki. Her actions are both helpful and manipulative, as she orchestrates situations for her own amusement and redemption.
Emotional Complexity and Confession: As her lies unravel, Yoshino begins to question her motivations. She develops guilt toward Aki, whom she genuinely cares for, and complex feelings for Masamune, resulting in emotional tension and eventual confrontation. Her journey shifts from playful manipulation to sincere attempts to repair the damage she caused.
Relationships
Aki Adagaki: Aki’s loyal maid and childhood companion. Yoshino is deeply devoted to Aki, though their relationship becomes strained as secrets come to light. Despite her betrayal, she ultimately wants to protect Aki’s happiness.
Masamune Makabe: Initially the target of her childhood deception, Masamune becomes an unwilling ally and emotional entanglement. Yoshino helps him get close to Aki but eventually falls for him herself, complicating the love triangle and forcing her to face her own feelings.
Neko Fujinomiya: Though they don’t interact much directly, Neko’s presence adds to the complexity of the romantic web, indirectly pressuring Yoshino to reassess her feelings and allegiances.
