Servant Coins was introduced in the 6th Anniversary of the game (August 2021 for JP, ~July 2023 for NA)
Players got retroactive coins (sent to the Inbox) for existing copies based on the Bond Level (all Rarities) and the Number of copies you obtained (4* and 5* only, Welfares not included) during the Anniversary.
Any future coins from Bond Up/NP copy are automatically added to your Coins Inventory
New welfare units got coins from their Event’s shops. Old welfare units will eventually get their coins
Currently (May 2022) only the following old welfares got coins: Elizabeth Variants (HW 2021), Bunyan (Learning with Manga Collab)
Those that had reruns after Anni6 also got coins in their respective events: Gray, Nobukatsu
Old welfares obtainable from Main Interludes/RP shop don’t give out coins
With the recently released Evocation Festivals, older welfares can now get coins via the shop.
Welfares get 480 coins from their Event or the Evocation shop. You need to raise the servant to bond 15 to farm the remaining 180 coins.