How do I fuse arks?

I just started the game and got a couple of the mission arks… Is there a way to fuse them to make a better one? Sorry if its a dumb question lol

Fusing is performed in a fusion building. These are located in certain towns, and only become available after you encounter…umm…idk the name, but it’s this one green-haired dude. It’s around the forest part of the main storyline.

Yeah U will find it out when u follow the storyline but if u want to know in every town there is one and its with a red and blue capsule thing on it , there u can see arks that u have and haven’t fused. To fuse them u need the recipes but dont buy them just follow the storyline and do the sidequests and then u will get all recipes to fuse the arks

Pretty much click the building with the test tubes. Then if you have both arks they’ll show and you can fuse