Illumination

1-3. Illumination (イルミナシオン); mellow mellow Vols. 1 to 3
Ryuuji and Naomi are close childhood friends. Both had their share of relationships with women, so Ryuuji is frustrated as to why he's had romantic feelings for the idiotic and oblivious Naomi all this time. While drinking his problems away, as usual, he meets the bartender Kiyotoshi who becomes interested in him, and the two ended up sleeping with each other. Since then, everything went spiraling out of control between the three of them, especially for Ryuuji, whose heart seems to betray him.

(Source: Manga Planet)

4. Love toka Iurashii (ラブとかいうらしい, Something Called Love); mellow mellow Vol. 4
5. Bara to Ibara to Barabara ...