These girls are probably more famous with the H!P crowd, but they're still a pretty important J-pop group imo. They were the least "H!P-ish" of the H!P groups, being a group that
didn't change its members at all, sang mostly rock-pop songs, and had amazing live tours with, occasionally, live bands.
They've been around since 2000. In 2009, they, along with the rest of H!P's "Elder Club", graduated from Hello! Project. They assured their fans that they'd stick together anyway, and started releasing collaboration singles and really taking off with their rock image and rock songs (that probably would NOT have happened had they stayed in H!P).
Then, in a final act of irony, they released their album MELON'S NOT DEAD and announced a tour of the same name. But unfortunately, they will be disbanding at the end of it, after 10 years of making awesome music. This is a huge blow, as most of Elder Club groups have been axed anyway (v-u-den, GAM, Coconuts Musume, Country Musume, etc.) but Melon Kinenbi was the one H!P group that had never wavered.
If you haven't, I'd suggest checking out their music, as they have some real gems (This is Unmei, Kawaii Kare, Saa! Koibito ni Narou, Akai Freesia, Girls Power Aisuru Power, Onegai Miwaku no Target etc.)
R.I.P. Melon Kinenbi
Source:
Here