Charm Up is basically leveling up a card by feeding it other cards in order to increase stats and level up appeal.
Once you select a card you want to level up, you will be prompted to choose which cards you want to use as feed.
※The charm up system changed Dec. 2015.
You can change your selected kare by pressing the blue button (変更する) under his icon.
Starting from the blue tab under the selected kare:
所持カレから: from your collection
ギフトから: from your gift box
表示切替: shows you various stats of your feed cards
level
attack
defense
cost
attraction points (total hearts filled)
おすすめ選択: recommended cards
will always be N cards
内容確認: confirmation of cards selected
will not start the level up
takes you to a confirmation page
You can select up to 20 cards to use as feed. The cards you will be using will be numbered as seen in the image to the left.
CAUTION: All your cards will be presented as feed options, no matter the rarity. However, your locked cards will be grayed out, so make sure you lock your cards. Organize cards by rarity as well.
I also don't recommend taking from the gift tab. Go to your gift box and take out all the cards you will be using as feed before hand.
After you click the blue button on the bottom, you will be taken to a confirmation page where you can review your feed cards.
決定: starts the level up
選択し直す: takes you back to the selection page
The max level of each card depends on the rarity:
N → 20
HN → 30
R → 40
HR → 50
SR → 60
SSR → 70
UR → 80(?)
The men cost for leveling a card is calculated like this:
For cards level 29 or under:
current level x # of feed cards x 50 men
For cards level 30 or over:
current level x # of feed cards x 100 men
For example, a level 1 card costs 500 men to level up when 10 feed cards are used, and a level 34 card costs 34000 men to level up when 10 feed cards are used.
Every feed card also give you step up keys of its rarity.
N: 1 N step up key per step up
HN: 2 HN step keys per step up
R: 10 R step up keys per step
HR: 20 HR step up keys per step up
SR:
SSR:
UR:
Appeal (アピール) is basically the skill a card has that helps give boosts during battle.
Below is a chart of the cards required to level up appeal:
※taken from the Japanese wiki
You cannot jump levels; it must be gradual.
Appeal resets to level 1 for every step up so it is recommended to focus on appeal leveling only after you've fully stepped up the kare.
The card(s) used do not have to be the base rarity; for example, you can make an R card from 3 HN cards and use that for appeal leveling.
You also don't have to use the exact number of cards; these numbers are for a 100% chance of level up. When on the charm up page after choosing all your feed cards, you can see this text, アピールLvUP成功率, plus a numbered percentage next to it. This is the success rate for a level up. 50% or more will probably be successful most of the time.
Eins (アインス) and Zwei (ツヴァイ) are cards specifically meant to be used as leveling material.
Eins is a R card and Zwei is a N card. They also have the three main types that the kares have: king, prince, and knight.
Eins and Zwei cards can be obtained sometimes as an extra from the Doki Doki Map, but they are more commonly obtained from event gachas.
They also help to lessen the amount of material and men used for leveling as they give more exp than other cards.
Eins and Zwei do not give out step up keys, nor do they count towards appeal leveling.