After Masato drinks too much and confronts someone at their house, the next scene shows him passed out sat at a table, with v* visible on the floor beneath/he wipes it off his face when he wakes up.
Not on screen. However, at one point the protagonist visits a museum's exposition on the history of Japanese occupation in Singapore. A story is told about a Japanese soldier brutally murdering a baby. Surprisingly disturbing moment in an otherwise rather light hearted movie.
Maybe not abusive, but Masato's father is emotionally distant and his grandmother rejected his mother's decision to marry a Japanese person. Tension between parent and child is a core theme.
The Singaporean grandmother is hostile toward her half Japanese grandson and disapproves her daughter being in a relationship with a Japanese man, due to the Japanese occupation that killed her husband.
The mother of the protagonist has died before the movie starts, but we see many flashbacks with her. Early into the movie, the protagonist also loses his father.