Akihiko Usami, known as Usagi, hails from a dysfunctional, immensely wealthy family. His childhood was marked by neglect and isolation, largely spent writing alone in notebooks. During this time, a male tutor molested him, contributing to his emotional fragility. Akihiko primarily interacted with the family butler, Tanaka, who showed genuine concern. He lived in England for ten years before returning to Japan, further disrupting his stability.

A professional writer, Akihiko achieved early success as the youngest recipient of the prestigious Naomori Award at seventeen after colleague Isaka Ryuuichirou discovered his manuscripts. He graduated top of his class from Teito University Law School but pursued writing full-time. Under the pen name Yayoi Akikawa, he authored Boys' Love novels initially inspired by his unrequited love for friend Takahiro Takahashi. These early works carried melancholy tones, often described as sad and depressing. Akihiko consistently disregarded deadlines, causing frequent conflicts with his editor, Eri Aikawa, who managed his career closely despite his apathy toward fame.

Akihiko's romantic life shifted significantly. After years harboring feelings for Takahiro, he tutored Takahiro's younger brother, Misaki Takahashi. When Takahiro announced his engagement, Misaki recognized Akihiko's hidden pain, leading Akihiko to realize his true affections lay with Misaki. Their relationship began with Akihiko kissing Misaki to comfort him. After Takahiro moved to Osaka, Misaki moved in with Akihiko, transitioning from roommates to lovers. Akihiko shifted his novel inspirations from Takahiro to Misaki, softening his writing style into more enjoyable narratives, reflecting Misaki's impact.

Akihiko exhibits complex traits. Outwardly confident and self-assured, he possesses a calculated awareness of his strengths and flaws. Beneath a mature demeanor, he displays childlike tendencies: collecting toys like stuffed bears, building elaborate miniatures such as a Great Wall of China replica, and neglecting responsibilities like pet care. He frequently initiates sexual contact with Misaki as his primary expression of love. His possessiveness manifests as jealousy when Misaki interacts with others, including senpai Keiichi Sumi or editor Aikawa. Yet, he prioritizes Misaki's well-being, calming him during crises and affirming unwavering commitment. Akihiko's father noted his childhood fragility and tendency to internalize others' actions, traits that persisted until meeting Misaki.

Family dynamics heavily influence Akihiko. He resents his half-brother, Haruhiko Usami, whom he accuses of "always trying to take what's his," including Haruhiko's later proclaimed "love" for Misaki. His father, Fuyuhiko, adopted into the Usami family, initially opposed Akihiko's relationship with Misaki due to class differences but eventually accepted it. Akihiko shares his father's childish hobbies like collecting bear-themed items but rejects familial wealth, notably declining a 1.3 billion yen inheritance. His cousin Kaoruko Usami assisted him in learning basic cooking skills for Misaki's benefit.

Akihiko's development centers on overcoming emotional barriers. He struggles to articulate feelings verbally, relying on physical intimacy instead. Anxiety about losing Misaki fuels overprotectiveness, which Misaki sometimes finds suffocating. However, Akihiko demonstrates growth by openly reassuring Misaki during conflicts, such as when family friend Manami suspected their relationship, vowing never to let him go. He acknowledges how Misaki transformed his life from loneliness to experiencing romantic happiness.