Mashita no Fudanshi-kun by KUROIWA Chihaya

Summary

Plot: Sokabe is a gay salaryman who lives in an apartment far away from his company because of his crush on his neighbor Motoi. One day, Sokabe stumbles on Motoi’s very large collection of BL manga that immediately catches his attention and in a panic he ends up being mistaken by Motoi, who is a hardcore fudanshi, as a fellow BL enthusiast. Now Sokabe must find a way to either confess his feelings or forever keep his silence as Motoi drags him into the world of sexy semes and blushing ukes.