Overall, it’s easy to see why The Miracles of the Namiya General Store has become so popular. Keigo Higashino sets out with an ambitious idea involving time travel and a lovable bunch of characters, which successfully draws the reader in.
<-- Higashino fan here, ever since I read Shimotsuki Kayoko's Manga rendition of Houkago (a.k.a. Afterschool, the novel which was Higashino's debut.)
If you want to continue digging yourself through his bibliography, Devotion of Suspect X is the no brainer in terms of western releases. It also is a good gateway novel to the whole Honkaku/orthodox mystery genre.
If you want to stick to the same sort of narrative structure there is Newcomer. It has pretty much the exact same sense of having separate stories, each which has some sense of catharsis in it and which are connected to each other. Only there it's not something supernatural, but a murder case.
(But that novel technically is one instalment in the middle of the Detective Kaga novel series. Only that the English releases are being selective in which books to release and worse, they don't just skip them, they change the order. But the stories are separate from each other, so can still be read stand alone. Just sometimes some details sip out and hang loosely around. The Detective Galileo series to which Devotion of Suspect X belongs is the same.)
If you want some more gut-wrenching stuff, there is Naoko and Journey to the Midnight Sun out in English as well. (The former might have gone OOP by now though.) The latter is quite and decades-wide spanning epos. (There is also a drama series adaption of it, which is also not bad. The interesting thing about the drama is, that it, in terms of reveals, starts where the novel ends. So whence the novel is like peeling an onion, the drama is like watching it grow. With the shift in focus it also clearly tells some pieces that are left obscure in the novel.)
In general I would say I can recommend just about anything* with Higashino involves as a writer.
(Even if some of the dramas are a bit... too much addressed for housewives-fanservice; the mystery core at least stays.)
Namiya stands definitely as the most optimistic (and child friendly) that I've read from his works list. So definitely makes for a good intro.
* The only thing that kind of stands out as a black sheep to me is the manga series Heads (art by the Ikigami artist). While not actually bad, it's just rather predictable and somehow missing out on almost everything of what I like about Higashino's works. Feels more in line with Ikigami's style of its episodic stories than anything else.
p.s. once you read through everything you can join me in the club of "No translation out there.... So many kanji.... x.x". And if you choose to go down the Honkaku rabbit hole even more so. @_@
@Luna I definitely intend to read the rest of his stuff! I'm leaning toward Devotion of Suspect X next and then go from there. I'll probably read everything available in English before looking to Japanese only titles, especially as hopefully by then my Japanese will be in a better position to tackle one...
I'm fascinated to see what his other books are like, given how family friendly and nice Namiya is in comparison to the usual stories he writes.