Koibumi to 13-sai no Actress

• Ja Kanji — 恋文と13歳の • Ja Romaji — Koibumi to 13-sai no Akutoresu • Genre — Romance

• Type — manga • Author — Jaga • Publisher — Houbunsha • Imprint — FUZ Comics • Magazine — Comic Fuz • First — September 20, 2022 • Volumes — 8 A Love Letter and a 13-Year-Old Actress is a Japanese manga series written and illustrated by Jaga. It began serialization on Houbunsha's Comic Fuz online service in September 2022, and has been compiled into eight volumes as of April 2026.

The series follows Fumi Isshiki, who works for the accounting department at JG Production Management. He is suddenly transferred to the company's management department, where he is called to serve as manager to Ayano Haga, one of their talents, until her manager came back from parental leave. As Fumi works with Ayano, the latter quickly becomes attached to him and later develops feelings for him.

• Fumi Isshiki • Previously working as an accountant at JG Production Management, he was transferred to the management department due to a worker shortage. He is temporarily assigned as Ayano Haga's manager while her regular manager Morioka is on leave. He quickly becomes attached to Ayano and becomes protective of her. • Ayano Haga • A 13-year old middle school student and talent at JG Production Management. She started her career as a child actress but put her career on hold to focus on her studies. Fumi is assigned to work with her as she resumed her career. She quickly becomes attached to Fumi and develops feelings for him. She was raised in a single-parent household with her mother.

The series is written and illustrated by Jaga. It began serialization on Houbunsha's Comic Fuz online service on September 20, 2022. The first volume was released on April 27, 2023. The series has been compiled into eight tankōbon volumes as of April 2026.