Kujira Daigo

Kujira Daigo by Sachio Umemoto (1943-1993)
pre-published in weekly Shonen Jump (1968-1970)
published in 2 volumes by Wakagi Shobo (Comic Mate)

The main character, Daigo, grew up as an orphan and moved to Tokyo after being adopted by a politician - The main story is about how he and his friends fight against the principal who plans to close down a night school / junior high!
'Daigo Kujira' is actually one of the eight works originally published in the very first issue of Shonen Jump (1968)
Since the cover of Jump stated; 'All Manga; All One-shots', this is officially a one-shot because only complete stories were published in every issue.
The cover of the first book issue also read; "The No. 1 manga by the No. 1 new manga artist.''
It's also the first completed work serialized in Jump magazine. In terms of the story, Daigo and his friends defeat the principal's conspiracy and win the continuation of the school in the final episode

Sachio Umemoto made his debut with a rental book manga called 'I Have My Dream' (Hinomaru Bunko) and soon after he started working as the assistant of Tetsuya Chiba (representative work; Ashita no Joe)
'Kujira Daigo' was serialized in 'Weekly Shonen Jump' (1968) but hating the exclusive contract he had, he left Jump and started working for 'Shonen King' (1970)
There he serialized 'Apache Baseball Army' that became a huge hit and was made
into a TV anime the following year to became a hit anime.
Other further representive works include 'Little Dan-chan' & 'Flying Wings'