Yuki Fumino - I Hear the Sunspot: Theory of Happiness Manga

Due to the overwhelming success of I Hear the Sunspot, the sequel has finally arrived, I Hear the Sunspot: Theory of Happiness! How will this "more than friends, less than lovers" relationship evolve?

Kohei Sugihara, a university student with progressive hearing loss, continues to navigate daily life and communication barriers with the help of Taichi Sagawa, whose blunt honesty and warmth bridge the silence between them. As their relationship deepens beyond friendship, both men confront misunderstandings, emotional hesitation, and the difficulty of expressing vulnerability in a world not built for accessibility.

Theory of Happiness focuses on mutual growth, consent, and learning how to support one another without erasing independence, expanding the emotional core of the I Hear the Sunspot series with quieter intimacy and maturity.

Japanese Name: ひだまりが聴こえる
English Title: I Hear the Sunspot: Theory of Happiness
Story & Art: Yuki Fumino
Original Publisher: One Peace Books (Japan imprint)
English Publisher: One Peace Books
Release Years: 2018–2019
Volumes: 2 (completed; part of the ongoing I Hear the Sunspot series)
Age Rating: Teen (T)
Genre: Boys’ Love (BL), Slice of Life, Romance
Themes: Hearing Disability, Communication, Emotional Vulnerability, Mutual Support, Everyday Intimacy

Adaptations

Live-action Japanese film adaptation released in 2017 covering the early series.

Other Notable Works by Yuki Fumino

Yuki Fumino is also the creator of I Hear the Sunspot: Limit and I Hear the Sunspot: Four Seasons, which continue Kohei and Taichi’s story with a focus on adult responsibility, long-term communication, and emotional continuity, reinforcing her reputation for gentle realism and socially grounded BL storytelling.

Comics & manga are assumed VG+ or better unless otherwise noted. No broken spines, no writing, no stickers, and may have light shelf wear. Mid-2000s or earlier manga may have slight yellowing due to the age of the paper. All manga and comics are assumed to be pre-owned.