Searching a J-rock (I believe) band

When I was younger I used to listen to a band a lot. It was so happy and hyperactive. Music clips with lots of colors. One of the band members was a bright with long hair blonde girl who eventually came out to be a guy.

I remember in one of their video clips the guys in the band would be flirting with the girl while sitting at school. Which was totally cute xD.

Eventually the band broke and they gotten a new member. One which almost looked european and played on a keyboard. This is when I stopped listening to their music and eventually I lost their older songs as well. At the same moment I was a huge fan of The Gazette which I think was in 2008 or so.. so I assume the other band was around the same time .. I just got no idea what it was called anymore. Can't find it anywhere and craving for the happy colors and music again. Could someone please help me who recognizes this and give me the name?

Thank you in advance!

(Sorry for the repost. I forgot to turn mail notifications on)

Sing!
http://www.midomi.co.jp/
https://youtu.be/LMLTi1TNXHY
https://youtu.be/5-AJaIQE6-E

sounds like an cafe but i could be wrong
https://www.youtube.com/watch?v=Q3y-80HBM6Q

100 % sure it's an Cafe xD my friend was crushing on Bou.

if you say school im not sure if you mean this https://www.youtube.com/watch?v=y37znARQdck
but then again i didnt see the videos i only heard the music ^^'

It's probably An Cafe your talking about, but if it is not An Cafe one other possibility is the band Oyuugi Wagamama Dan x [PaRADEiS] because the singer of that group looks alot like Bou from An Cafe. But most likely you are talking about An cafe since they had a school pv.