Komatta Toki Ni Wa Hoshi Ni Kike!
If I had to choose this is probably my favorite manga, I have read it more times that I can count and I love it everytime. Despite not having an explicit romance or even much kisses I think it's hundred times better than other mangas that do have it. I think it's the best manga from Abe Miyuki and if you're a fan of her or Super Lovers (you can see characters like Ren and Haru) you won't regret giving it a try. The style becomes better and better every chapter and you can see a character development. Least but not last, this manga has it all (or almost lol) you can feel so many emotions while reading this. I wish Abe Miyuki writes some extra story about them in the future (nothing is impossible)
Hana wa Saku ka
18 Unlimited
It's similar to 19 days, I can't really tell if it's just bromance or it will turn into romance at the end
The One Manhua