Amagi Brilliant Park? Fumo

Kanie Seiya, a genius with both looks, intellect and athletic ability is suddenly threatened on a date to a park by the new transfer student. Turns out, the park is run down and the princess managing it wants our narcissistic main character to take over and save it! By the author of Full Metal Panic!

Amusement parks are places of wonder and fun for all ages... right? Well, that's not quite the case for Amagi Brilliant Park, a "crummy" amusement park on the outskirts of Tokyo where the snacks are inedible, the attractions are falling apart, and the mascots regularly get into fistfights with the guests. It's the kind of place that cool, handsome, brilliant Kanie Seiya wouldn't be caught dead in... until a mysterious girl drags him there--at literal gunpoint--and demands that he help them save the park! (Source: J-Novel Club)