Just before the summer holiday, Mana completely forgets to apply for a hands-on training course. Almost all of the courses are already closed. When she is at a loss as to what to do, one beautiful woman offers her a hands-on training course that is still available. She accepts it without checking what she is going to do.... Her course is at a sanatorium. A patient whom she takes in charge is Wataru. His days are numbered and he suffers from mental illness as well. Mana works hard for him but she gets mentally unstable day by day. At last, she decides to leave the sanatorium... but it stimulates his crooked sexual desire and Mana becomes his sex slave....