Jun'ichi Hoshiyama, publishing under a pen name while his real surname is Toriyama, is a successful romance novelist haunted by obsessive-compulsive disorder. His condition manifests as psychogenic vomiting during intense anxiety over potentially reusing plot ideas from his own past work. This anxiety strikes during brainstorming sessions, triggering compulsive checks of his published novels as he fears his new concepts lack originality. Visually, pink feathers symbolize his vomit, and a rooster or chicken motif reflects his creative anxieties.

Professionally, Hoshiyama feels trapped by commercial success built on writing relationships between older men and younger women—a formula criticized as repetitive. This conflict worsens his distress as he struggles to balance artistic integrity with market demands. His therapy with Dr. Ichirō Irabu confronts this creative burnout; Dr. Irabu identifies routine as the core problem and challenges Hoshiyama to break his established patterns.

A pivotal element of his past is his early novel "Ashita" (Tomorrow), written with emotional depth but poor sales, contrasting sharply with his later commercial work. Colleagues and friends reference "Ashita" to remind him of his authentic voice before financial pressures took hold. His journey resolves by reconnecting with this authenticity, culminating in a cathartic public confrontation with a rival author that releases his suppressed emotions.

This character is adapted from the female protagonist Aiko Hoshiyama in the original literary source; the anime version alters the gender while retaining the core psychological conflict.