I Hate You More Than Anyone (1997)

Blurb:
Kazuha Akiyoshia responsible girl whose time is always taken up with helping her parents take care of her younger siblingsfinds herself dealing with romantic relationships for the first time in her life. Is Kazuha seriously thinking about becoming a hairdresser, or is she only considering it because its Sugimotos career and represents a way to get closer to him? Meanwhile, theres trouble at home when her brother, Chizura, starts hanging out with the wrong crowd. Unknown to Kazuha, Sugimoto steps in to try and help the troubled Chizura, but his advice might just lead to a serious rift between Kazuha and Sugimoto.

Source: www.anisearch.com/manga/3287