一途な片思い、実らせたい小さな幸せ。 (Ichizu na Kataomoi, Minorasetai Chiisana Shiawase.)

Background
The song was uploaded before Mayu's release as one of the tracks to be featured on Mayu's special compilation album by EXIT TUNES. It has gained over half million views since and it's currently Mayu's most popular song.

It's also the third song in Utata-P's "Happinness" series.

The song is about a seemingly normal schoolgirl, starting her day and anticipating the meeting with her "beloved person". Even though she doesn't really approach them, she is happy to just see them from afar. As the girl speaks about the person she loves though, the song takes an unexpected twist and it's revealead she is in fact a stalker, obsessed with her crush to the point of planning on killing everyone that gets close to them.

The song can also be found on Utata-P's first album Minna Shiawase ni Na~re!