Tsumugi-kun no Sakippo

Two childhood friends have a long-standing private habit: one of them regularly allows the other to suck on their chest. What began as a way to comfort the other has evolved over time, especially as they grow older and physical changes occur. The dynamic between them shifts as they navigate adolescence, and their relationship becomes more complex. One is described as an arrogant sergeant, while the other has no living relatives. The story explores the development of their bond, with an additional chapter included.