Well, actually, its not as easy as it sounds according to BemaniWiki

Bitter Chocolate Striker

• Get 100 full combos or more on charts from Empress (yes, I said charts, not songs)
• Hard Clear AAA a song by L.E.D. that is an 11 (10 on double) or more.

Colorful Cookie

• Have a score on every Expert course
• Hard Clear AAA a song by DJ Yoshitaka that is an 11 (10 on double) or more.

不沈艦CANDY

• Have a score on every DJ Taka song
• Hard Clear AAA a song by DJ Taka that is an 11 (10 on double) or more.

Have fun :3