The Unwanted Undead Adventurer Saison 1 Épisode 12

Rentt Faina has hunted monsters for the last 10 years. Sadly, he’s not great at his job, stuck hunting slimes and goblins for a few coins each day. His luck turns when he finds an undiscovered path. At the path’s end, he meets his demise in the maw of a legendary dragon. But, he wakes up as an undead bag of bones! He sets out to achieve Existential Evolution and rejoin the land of the living.

A young kid infects a girl and then the two start attacking, biting and infecting everybody else.