You can just put any novels that you think that deserves more attention, I love to dig but I want to see other people's preferences and recommendations

There are many underrated novels and I could make a large list, but I want to ask few questions first.

Underrated where? Here at MangaUpdates, or at Novel Updates, or maybe in English-speaking community as a whole?

What kind of novels are you looking for / interested in? Maybe some specific genres, elements, or themes?

Edit:
You didn't reply, so here are some good novels that I think deserve more attention:
Ame no Hi no Iris (Novel) + Koori no Kuni no Amaryllis (Novel)
Fremd Torturchen (Novel)
Gekkou (Novel)
Mimizuku to Yoru no Ou (Novel)
Murasakiiro no Qualia (Novel)
Owari no Chronicle (Novel) + Kyoukai Senjou no Horizon (Novel)
Rokka no Yuusha (Novel)
Sayonara Piano Sonata (Novel)
Seikai no Monshou (Novel)
Shinsekai yori (Novel)
Shuumatsu Nani Shitemasu ka? Isogashii Desu ka? Sukutte Moratte Ii Desu ka? (Novel)
Sugar Dark (Novel)
Tabi ni Deyou, Horobiyuku Sekai no Hate Made (Novel)
Tada, Sore Dake de Yokattan desu (Novel)
Tatakau Shisho (Novel)
Toaru Hikuushi e no Tsuioku (Novel)

Don't necessarily think he's underrated, but I think more people should look into Shusaku Endo's work.

Nidome no Yuusha