Historical novel author suggestions:
藤沢周平 is, as mentioned, my personal favourite. He likes to write stories about low-ranking samurai who have to deal with situations where they’re constrained by their societal rules, their sense of duty, etc; usually the settings and plots are internal to some small clan (e.g. somebody gets caught up in internal clan political faction struggles), and the endings are often bittersweet. There are both short stories and novels. I would suggest starting where I did, with 用心棒日月抄, which is about a samurai who falls out with his clan and has to scrape a living doing various “bodyguarding” jobs in Edo while he tries to search for evidence that could clear his name. But I haven’t read anything by the author I didn’t like.
赤川次郎 mostly writes mystery/adventure stuff, but his one historical series, 鼠, is a fun easy entry to reading historical novels for people who worry they might be a bit of a slog to read. The books are all short stories featuring a robin-hood style “rob the rich and help the poor” Edo thief.
葉室麟 is good too. His books seem to have a romance-ish theme or tinge to them (though my sample size is only three). I have put one of his books into the nominations for the Advanced Book Club (voting next week, I think).
宮部みゆき is another mostly-mystery-fiction author who’s dipped a toe into the historical fiction genre, and who I found a straightforward read.
京極夏彦 and more specifically his 巷説百物語 series. (He’s also done some crime fiction.)
Anybody listed above as also doing crime/mystery
松本清張 I talked about above. I think 点と線 is one of the often-recommended famous books, but I vaguely recall it being a bit lighter on the social issues side of things and a bit more police-procedural. ゼロの焦点 is another I liked; it’s set in post-WW2 occupied Japan. (松本 also wrote historical fiction but I have found it rather dull and hard to read compared to his crime novels.)
内田康夫 is another of those “wrote over a hundred books” prolific authors. Most of his feature amateur detective Asami Mitsuhiko. There’s often an element of travelogue to them, with the action in each book typically taking place in some different tourist region or remote location in Japan. I think I’d say I recommend these if you happen to like crime fiction anyway; I like them but I’m not sure they have enough to commend them to somebody who isn’t already a genre fan. As with all these “wrote a ton” authors, the advantage is that if you like the writing style then there’s a lot available to read.
貴志祐介-- author of 新世界より (SF, strongly recommended) but he seems to mostly write crime fiction. Modern settings, quite fond of locked room mysteries and other kinds of “how was it done?” puzzle-ish plots.
佐々木譲 does good police-procedurals; the ones I’ve read have tended to have a “police corruption” theme.
横溝正史 wrote in the 50s and 60s mostly; the settings are usually in that era. There’s a book club on the forum going through most of his novels.
江戸川乱歩 you already know about.