The Kamisato Clan Housekeeper is a Pyro character character and before unleashing his might on the enemy you will first need to upgrade the character a little. Here is the complete list of the materials needed for Thomas.
Thomas Ascension Materials
Thomas Talents Upgrade Materials List
If you're looking to upgrade your Ayaka here is the complete list of the materials you'll have to farm to Ascend the Cryo dignified heiress and her talents.
If you're looking to upgrade your Fischl here is the complete list of the materials you'll have to farm to Ascend the electro edgy girl and her talents.