Tamaki Yuminaga is a friendly guy who smiles a lot, and Shunta Shii loves seeing that expression of his. The two are one year apart, and they’ve been friends ever since they were little, always hanging out despite Tamaki being ahead by a grade. However, as time passes, Tamaki starts to change little by little. And, something starts to change in Shii, too, after he witnesses Tamaki crying in front of his apartment door. Shii believes his own feelings are impure, ugly, and wrong. As his self－imposed list of things he should never do grows, his relationship with Tamaki takes a sudden turn in high school...