1. Hellfire
2. Lesson,Training&LimitClear

This is the Lesson screen. Here, you "feed" a units to a base card, the one you want to level up. Once the lesson is over, the feeder cards disappear. Each card's rarity gives it a maximum level cap, so rarer cards are naturally stronger when trained.
For that reason, dont train cards weaker than SR, since they will either be fed to your better cards, or sacrificed to expand the bank. Remember to only train evolved cards, because if you evolve them later, you lose the levels they had.

The higher the rarity and level, the cost of feeding cards increases to the level of the base card.
You can also get a bonus of experience by performing a lesson with girls of the same attribute.
Sometimes, when a lesson is completed, it can end with a Big Success. When that happens, the experience gained goes up by even more.

You also want to feed trainer cards, and sell your Common or Uncommon cards. At higher levels, you will just be wasting high amounts of Ero for very little % of experience.

NOTE: If a card is in your deck, you cannot use them as a feeder card. You can use a card already in your deck as a base to level up.

This training screen is also known as evolving. Card will show up on the right, as long as you have 2 copies of that unit. By putting a card in the slot under base, the left will filter only other copies of that unit.

When you train the same girls together, they merge and evolve into a different card. Their appearance and abilities change. They revert back to level 1, and gain a (+) after their name. The new card will be the same girl, and the new picture will be similar to the earlier form (usually same scene, but more sexual)

When you train them, some of their skills, attack and defense power will be maintained.
The affection level for the two of them will be added together and carried forward.

NOTE: Once a girl has been trained (a plus sign (+) appears next to her rarity), she cannot be evolved further again. After that, its called Limit Clear

NOTE: You start from level one after training.
NOTE: The card used to feed the base card in will be lost.

When either the base card or the materials card is at maximum level or Max. Affection Level, a maximum bonus value is applied to the base card's attack and defense strengths.
NOTE: When both the level and affection level are at maximum, bonus values for both are applied.

When you re-evolve a trained girl, she can clear her present limits on strength, increasing her maximum level, attack and defense strengths.

You can clear limits by selecting a trained girl, marked as card name+, for the base and then use the same girl, just like if you were evolving her again.

Every time you reach limit cleared, the maximum level goes up by three. There's no restriction on the number of times you can perform limit cleared, but the maximum level can only be increased ten times, for an increase over the original maximum level of +30.

Rarity	Maximum Value (Level)
Ultimate+	150
Legendary+	130
Ultra-rare+	110
Super Rare+	100
Rare+	80

Even after you've maxed out the level increases, performing more limit cleared moves will further increase your attack and defense strength.

Limit Clearing Trainers can be used instead of girls when performing a limit break.
Limit Clearing Trainer cards rarity can go from Rare to Ultimate and can also be used for girls with a lower rarity level.

(Example) If the base is a Ultra Rare + card
・Trainer cards that can be used as raw materials when clearing a limit: Ultimate Limit Clearing Trainers, Legend Limit Clearing Trainers, Ultra Rare Limit Clearing Trainers
・Trainer cards that cannot be used as raw materials when clearing a limit: Super Rare Limit Clearing Trainers, Rare Limit Clearing Trainers

• The increase in the attack and defense strength when a limit cleared is performed is not affected by the level or affection level bonus of girl who is the material.
  
• For every one girl who becomes a material, the count toward limit cleared is increased by one.
  
• Girls that can be materials for limit cleared are limited to those that are the same as the base card, or girls who have never been trained.