To increase performance and stamina of unit member, you can do Lesson. Other card is required and will be gone once used to "feed". You can also use "Shirabe Narumi" sensei cards that are obtained as event rewards or from song rewards.
If the material card has same color with the girl card, the material card will give 1.2x bonus EXP, Great Success will increase the EXP gained by 1.5x
Since update 1.7, the LESSON START word when feeding has been replaced with POWER UP START.
|Rarity||EXP Gained||Same color|
|Shirabe Narumi (N)||100||120|
|Shirabe Narumi (R)||300||350|
You can also increase the skill level of the girls by doing Lesson. To increase skill level exact same card is required (base rarity will also count if you evolved the card). "Ema Fukami" sensei cards of the same color as a girl may also be used to improve skill levels, with the probability of a boost increasing with the number of cards used up to a maximum of 100%.