 If you liked
Strike the Blood
|
 ...then you might like
Engage Kiss
|
Similar in terms of setting; both have their main focus on artificial cities that are afloat out in the pacific but still technically under Japanese jurisdiction.
Also, the events surrounding those cities are predominantly supernatural. In Strike the Blood's case vampires, and for Engage Kiss demons. From that, the main character's powers are relied upon to keep the city's peace.