Through the power of the Eternal Mangekyō Sharingan you gain the ability to manipulate the Flames of Amaterasu, fire that has the power to burn even that which cannot be burned. Amaterasu Flames can burn fire, water, and even chakra itself, and cannot be put out until it burns itself out. You cannot control this flame on your own, but summon it at a point you look at.
Project V17/Powers/Shardless/Eternal Mangekyō Sharingan Abilities/Mangekyō: Amaterasu
From Worm CYOA Wiki
Daikokuten
From the consumption of the Chakra Fruit you have been given the gift of chakra and its two composite parts, Yin and Yang. The black flames of Amaterasu have revealed the secret to its mystical nature and with it came complete understanding of, and the ability to freely and effortlessly manipulate Yin. Yin governs Imagination, giving form to nothing and everything, and is the reason behind almost every jutsu's effects. Almost every jutsu uses a mixture of Yin and Yang, one to give form to imagination and one to bring imagination into reality. With your understanding of Yin, you can now perform things such as animating your shadow, turning fire solid, or creating black lightning that is far more potent than regular lightning. While your mastery of Yin is incredible, its true strength is shown when used in conjunction with its counterpart.