Just finished reading Volume 1 of this manga, and I highly recommend it:
https://hiwamatanoboru.com/2021/09/06/seciton-chief-shima-kosaku-volume-1/
I can't believe manga aggregator sites haven't uploaded this piece yet.
Section Chief Shima Kо̄saku
It’s a manga known for its realistic depiction of life as a salaryman (which is sort of a slang term for a male office worker) working at a major Japanese company and its office culture and that sort of thing. It’s a slice of life drama about making one’s way in the corporate world and the emotions he experiences involved with that. It also has themes of management strategy, the main character’s relationships with women, mysteries, and office politics. Also all kinds of crazy weird shit happens.
This series is kind of the archetypical seinen manga. And it’s one of the series a lot of Japanese readers will think of immediately when thinking about manga for adults. The main character, Shima Kо̄saku, starts out at age 34. It’s a series well known for its realistic depiction of office life and about the things actually going on in Japan at the time.
As of now, the series is still on-going and the series breaks down into parts. They go something like this:
(Part 1) Section Chief (Kachō) Shima Kōsaku 1983–1992: 17 volumes
(Part 2) Division Chief (Buchō) Shima Kōsaku 1992–2002: 13 volumes
(Part 3) Managing Director (Torishimariyaku) Shima Kōsaku 2002–2005: 8 volumes
(Part 4) Executive Managing Director (Jōmu) Shima Kōsaku 2005–2006: 6 volumes
(Part 5) Senior Managing Director (Senmu) Shima Kōsaku 2006–2008: 5 volumes
(Part 6) President (Shachō) Shima Kōsaku 2008–2013: 16 volumes
(Part 7) Chairman (Kaichō) Shima Kōsaku 2013–2019: 13 volumes
(Part

Senior Advisor (Sōdan’yaku) Shima Kōsaku 2019–present: 4 volumes (Ongoing)