Tuon like Grove was sent with a large company of miners as part of the Central Expanse. He is first encountered in Chapter 1 in Cavern System where he and his party were ambushed and assimilated by several Slime Dragon. Tuon acts as the final boss of Chapter 1 where he under the control of his Sybmiote will attack Grove with the intent to assimilate him as well.

After freeing Tuon and his team he will open a forge and upgrade the Inn and surrounding area into a small colony, as well as assign Grove on a quest to find additional resources and missing workers.

It is heavily implied that Tuon has become tainted/corrupted by the Slime Dragon. Various workers note that his eyes were not the glowing pink that they are now, and that he did not used to look at the males the way he does now. He is also shown to have a high amount of Libido and Sexual Frustration that cannot be relieved through conventional masturbation. Tuon is implied to also be attracted to Grove as there is a scene where he uses pieces of Grove's Slime Dragon symbiote to make a sex toy based on Grove's Butt.

After Chapter 4: Dark Places, Tuon manages to capture a corruptive vampire bat which he uses as his own personal concubine in order to sate his lusts.