Shodai Nekketsu Kōha Kunio-kun/Ki powers

Ki Power (きりょく) is similar to mana which is used to power magic-like effects. All restorative effects are permanent but boost effects are purely temporary and will run out very quickly. Ki fully restores when you sleep in your bed (which is located at the middle room at 2/F Hotel Osaka), so if you know you are going to return home soon you might as well use it up to make things easier.