Kochikame (1976)

Kochikame (Kochira Katsushika-ku Kameari Kōen-mae Hashutsujo, こちら葛飾区亀有公園前派出所), Osamu Akimoto's gag manga, was serialized in Shueisha's Weekly Shōnen Jump from issue 42 of 1976 to issue 42 of 2016, collected across 200 volumes, a Guinness World Record. It follows Kankichi Ryotsu, an eccentric, scheming police officer at a small Tokyo koban, through episodic comedy built around whatever fad or gadget was current when each chapter ran. (Wikipedia)

Watches

Seiko (unidentified model): In ch. 4, "For Sale!! The Right to Appear in Kochikame" (売ります!!こち亀登場権の巻), a wealthy background character (Shiratori Reiji, per a fan-blog synopsis of the volume) shows off his fortune, only to be overshadowed the moment fellow officer Nakagawa arrives; Nakagawa wears a plain Japanese-made chronograph. Begin magazine's own manga-watch feature identifies the brand as Seiko, hedging ("おそらく", "probably") that the specific piece is a chronograph nicknamed "Speedmaster" by collectors for its three-subdial layout (not an actual Omega), released around 1989; a contemporaneous X/Twitter discussion of the same scene and reply thread reaches no firmer consensus, with one reply suggesting a Grand Seiko instead. Neither cited account establishes legible dial branding. A scan of page 82 of the volume shows the exchange itself: Ryotsu asks which maker Nakagawa's watch is, and Nakagawa answers "Seiko" (セイコーですが) over a close-up of a three-subdial chronograph; the drawing gives no model. (Kochikame, ch. 4, p. 65, vol. 93; Begin; X/Twitter; igmonostone)
© Osamu Akimoto / Shueisha; scan via animanch.com

PREMICO Kochikame Ryotsu Mechanical Watch: Official product partnership, not an in-work appearance. Imperial Enterprise released this automatic skeleton watch November 20, 2017, marking 40 years since Kochikame's serialization began, supervised by creator Osamu Akimoto, limited to 4,000 pieces, its dial cut into a skeleton opening shaped after Ryotsu's eyebrows and a beigoma spinning top. It is licensed merchandise, not worn on screen. (PREMICO; atpress)

Official partnership product · Not shown in the work