Happiness Series

The Happiness Series is an exteremely popular ongoing series of songs by Utata-P (music) and Torii Hitsuji (lyrics), and illustrated by wogura.

Background
The songs, while having different topics, all deal with Happiness, whether it be their own, or someone else's.

They also all have the same type of thumbnail in NicoNicoDouga (shown in the pictures below).

All four songs will be featured on Utata-P's upcoming album, Minna Shiawase Ninare!.