The mysterious trophy DDDD8

so yeah i come back here on forums every once in awhile to check things out a bit o U o ==b
but today when i came i saw an extra little thing under my avatar? ive been in sakura no ame but i never did my ytc story or any of that stuff. but im still not even clear what ytc story is, i think it was some event when the chorus battle first started or christmas or whenever i dont even know D8 but if it was an event then i never participated it and i hav never seen that trophy on me ever before until today? unless ytc story is something else? :O Then i have no idea... i feel bad to carry a credit of something i havent done . v . So if someone can remove it or explain to me what it is im good :3