I'm looking for slice of life manga that focuses on brother-sister relationship like in Fudatsuki no Kyoko-chan. Although Fudatsuki no Kyoko-chan contains some supernatural stuff, I would prefer a story that isn't out of this world, just purely about their daily lives like going to school and stuff, typical SoL, and no demon slaying or whatever stuff like that, you know what I mean. Also, I would prefer something that isn't ecchi. I don't mind it having any incestuous stuff (it's brother-sister so it can't be avoided), but it'd be better if there aren't. Something funny and cute like the relationship of the siblings in Fudatsuki no Kyoko-chan. Thank you. 😀

Try Machida-kun no Sekai for a calming, lovely read (everything is so relaxing and beautiful! The protagonist is a sweetheart, too). Definetely the best SoL I've ever read.
Sakamoto desu ga? is a good choice if you wanna laugh.
If you like soft and comical romance you could also try Gekkan Shoujo Nozaki-kun (in my opinion the anime is more focused to the romantic part, both are great).
Hope you like them! ;D

Errr... Maybe Himouto! Umaru-chan or Hatarakanai Futari or If You're Gonna Dress Up, Do It Like This those are all the siblings slice of life I can think of

😀