The Anime Lad
Spacequakes have struck the world for thirty years. Shidou Itsuka meets a mysterious girl at the center of one and learns that she is a Spirit whose arrival can cause the disaster. His sister Kotori commands the airship Ratatoskr and recruits him. His assignment is to make a Spirit fall in love with him. Standard training may not apply.
Gigguku
Date A Live takes a world-threatening spacequake and gives the solution to one apparently ordinary high schooler’s love life. Shidou meets a Spirit, discovers his sister commands an airship, and gets the least normal assignment imaginable. Make the Spirit fall for him, then seal her power. Romance has become disaster management, and the escalation is immediate!
Father's Basement
The premise reverse engineers a harem from a disaster manual, and subtlety never enters the room. Still, the central contradiction has comic bite. Spirits are treated as threats because their appearances cause spacequakes, while Shidou is asked to approach rather than destroy them. The method is absurd and ethically messy enough to create real friction.