Anata wo Shinjiteru (I Believe in You)
by MIURA Noriko
Status in Japan: 1 volume (complete)
The main story is about a teenage girl who's life has become a living hell because of her alcoholic father. Moreover, her mother seems to love her little brother more than her and she feels a lot of preasure due to the existing circumstances. All this has made her more mature than girls her age. Lately however, she feels some sort of connection with one of the "bad guys in school" who has been showing kindness to her younger brother. He takes both of them to the zoo after the father breaks his promise due to a hangover... (based on summary from momiji_mii's livejournal)
Other MIURA Noriko manga: Return, Kirai, Houkago Kindan Lesson etc.
Volume 1 Story1 part1
Volume 1 Story1 part2