Butterfly-Kera Kimura on youtube
This song was released in 2009.
She wrote this song for her best friends who was going to get married. 
Therefore this song is written from a person point of view who is celebrating her friend's wedding and marriage.
Her voice is very clear and cute and melody is very cute as well.
She is short and small and just like a doll.
In 2010, she got married with Eita who is a Japanese actor.
I guess now she is singing this song for herself:)