The following units cannot be obtained by gatcha or in-game events, instead, you have to input a serial code in order to get them, or if Serial codes are no longer available they are usually added to an in-game shop.
NicoNico codes are given to those who apply for the gift on the NicoNicoLive page while the promo is live (requires NicoNico Premium membership).
Bunkobons are small books (smaller than an average manga book) which is almost pure text with some images in each chapter (similar to light novels). While they're not translated, you can still order them and get the code (Amazon jp does ship worldwide)
You can find more info here and in the Flower Knight's respective pages.
All items (26)