To increase the Craft level, you need to proceed with the Promotion Trial.
■ Promotion Quest
① Tap the 'Promotion Trial'.
② The Promotion Trial quests are automatically tracked on the main screen.
You can also check it at: 'Menu' (=) - 'Quest' - 'Sub Quest'.
③ The production item for the Promotion Trial quest can be checked because it is marked as [QUEST].
④ Craft the Promotion Trial items.
⑤ When you complete the Promotion Trial quest, the Craft level is increased and you can get an additional ability.
※ The guide was produced in a separate test environment.
So, It may change depending on the update and development situation.
Thank you for your love and interest in the Devil Book~
Devil Book Team