Read Need a Girl hentai manga on hentaidexy,
summary for Need a Girl :
Three boys are desperately struggling to “make” a girlfriend in their sad adolescent lives.
They then realize that their classmate, Ghang Han-Gyul has been secretly going out with a beauty for 100 days (a 100 day celebration of a relationship is seen as very significant).
This triggers the friendship between the manly, serious Han-Gyul and the three dateless losers.