The Mankai Gauge appears in the form of a flower-shaped pattern on each Hero's uniform. The gauge is filled up every time a Hero deals enough damage, or blocks a strong attack. Once the Mankai Gauge is filled, the Hero may actively use it, or it will be passively activated after a certain amount of time.
Though it is stated that the Mankai Gauge is only filled by fighting, towards the end of the series it can be noted that if the will to fight and protect is strong enough, the gauge can be filled almost immediately and be activated.
- If one looks closely in the opening credits of Yuki Yuna is a Hero (the ending credits of episode 1), each Hero's Mankai Gauge is shown with an amount of it filled. This amount corresponds to the Hero's Mankai Gauge as of the start of that episode.