Inazuma is a bit different from the other nations in Genshin Impact, Mondstadt and Liyue. While some features like donating to the Statue of Seven remain the same, how you spend Electro Seals differs significantly. Electro Seals are given at the Sacred Sakura Tree, but once you reach it, you'll need to take your stuff elsewhere.
The electro sigil shop will be closed when you arrive in Inazuma Town and will only open if you meet very specific criteria. You must reach level 50 at the Sacred Sakure Tree to unlock the shop. This means you need to find and donate 1250 Electro Seals before the shop opens.
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Once you complete this task and claim your rewards, Netsuke no Gen Crafts in Inazuma City will open. This shop offers rare furniture, weapon ascension materials, and offers mora exchange. You will need to get a high completion rating on all islands to unlock this and open hundreds of chests.
The cost of unique items in the shop is much lower than the 25 Electro Seals required by the Sacred Sakura Tree, so clearing the shop should be much easier.
For more Genshin Impact content, see How to Use Secret Room Key in Enkanomiya in Genshin Impact on Pro Game Guides.