Mankai (満開, lit. full bloom) is a special power granted to Heroes who have expended a great deal of magic, granting incredible power unique to the user for a limited time.
Every Hero has a Mankai gauge on some part of her uniform in the form of a five-petaled flower. Using large amounts of magic or blocking powerful attacks will cause one of the gauge's five petals to light up, and once all five petals have been lit the Hero can activate her Mankai form. However, once all five petals are lit, a Hero's Mankai will activate automatically if they do not actively use it for some time.
When a Mankai is activated, rainbow-colored roots of energy will spring up from the Jukai and surround the user in light, before the light explodes into an enormous, flower-shaped aura. The user's Hero outfit changes into a long robe with detached sleeves, a uniform reminiscent of traditional Miko uniforms. Their weapon will also become a much stronger version of their main weapon.
The Mankai involves the Shinju granting a portion of its own power to a Hero, and thus it requires a sacrifice in return. This sacrifice is called the Sange (falling flowers). After a Hero's Mankai dissipates, she will permanently lose a bodily function in return: for example, the usage of a limb or one of her senses. The Sange stacks, and the more times a Hero uses her Mankai form, the more parts of her body she will sacrifice for the Sange. After Sange, a Hero's outfit will be modified to help make up for any missing functions; for example, after Tougou lost her legs to the Sange, her outfit developed ribbons that help her to move around.
After each Sange, the Shinju will grant the Hero a new fairy; thus, the number of times a Hero has used Mankai can be calculated by subtracting one from their total number of fairies. For example, Sonoko, who activated her Mankai a total of 20 times, owns 21 fairies.