Exact details vary by scanlation group, but the consensus for is:
: A recurring symbol of Terumi's trauma was his inability to drink milk (associated with his bullies). In the final pages, he is shown drinking milk comfortably, signaling he has finally "lifted the curse" of his past. A New Beginning minamoto-kun monogatari 359
The Empty Vessel Pages: 24 (Standard monthly release) Exact details vary by scanlation group, but the