Hey there @vs_studio! I’m mostly support for the actual use of the engine, but I can answer this as I’m also an indie developer who uses unreal.
The specifics should be listed here in the EULA
When reading through pay extra attention to chapters 1 - 6, and then the Royalty Addendum section 1 - 7. You must determine if your service/product would qualify to have to pay the 5% royalty first, as it’s usually after $1mil USD in sales in total lifetime, but certain business types and layouts would be subject to the 5% regardless.
If this is a bigger operation you may have to look into custom licensing.
This would be the link to look into your licensing options and contacting the licensing team. Unreal Engine (UE5) licensing options - Unreal Engine
I noticed you mentioned Yen as the currency, so I would request to check and see if the rates are different in the other language versions of the EULA as I only have experience as a developer in the US. Hope this helps!