Hastur is a powerful being from another world, currently studying at Ueno Academy in Tokyo. He appears as a bipedal lizard and uses a yellow biohazard suit during emergencies. Hastur commands insects and can manipulate wind and poison. He has a complex relationship with humans, wanting to protect them but unintentionally frightening them due to his appearance and abilities. He is a valuable asset to Ueno Academy, helping to contain dangerous pathogens, but also poses a risk if his powers are misused. He works mostly independently, accompanied only by his beast, Pazuzu. Hastur is highly concerned for the guild's human guildmaster.