Hana, the heroine of this work, was an ordinary schoolgirl until her birthday this year. On Hana's birthday, she received an email from her deceased grandfather, sent by timer. The email contained the address of a certain cafe, with only one sentence: 'Once you arrive, follow the instructions of the staff.' As soon as Hana arrived at the cafe, she found four male employees there. One of the employees immediately ordered her to help out. That day, Hana was suddenly attacked by a monster, but was saved from her predicament by the cafe employees. They were the Soudou Sentai Goukengo, warriors who protect the peace of the Earth! It turns out that Hana is also a member of Goukengo... What fate awaits her...? [BAD END]