two young people with severe phobias—Kengo Kosaka, who has mysophobia (fear of dirt), and Hijiri Sanagi, who has scopophobia (fear of being stared at)—who meet and fall in love. They find solace and connection with each other due to their shared social isolation, but their relationship is complicated by the "parasites" in their heads. While it appears to be a story of two people with mental health issues falling in love, the parasites are a literal, parasitic presence in their brains that cause symptoms and affect their lives.