Name: Shimotsuki Taiyo
Age: 5 years old
Templates: Yoriichi Tsugikuni and Akiko Yosano
Talents:
From Yoriichi;
Demon Slayer Mark: having been born with it and possessing the tremendous physical abilities granted by its effects throughout his lifespan. Unlike all other users of the Mark in his era, which cursed them to die before the age of 25, Yoriichi was able to defy fate and lived to about 85 years of age. It is presently unknown why Yoriichi is immune to the Mark's effects, but it is presumably because he was born with it, unlike other Demon Slayers who have to obtain it themselves.
Transparent World: Yoriichi had access to the Transparent World since birth, and could use it with incredible proficiency, evident when he could watch for lung expansions and muscle contractions within a person and surmise when to strike them as a child. This ability also granted him an advantage against Muzan, allowing him to find his weaknesses instantly and overwhelm him.
Selfless State: During their confrontation, Muzan noted that Yoriichi emanated no sense of drive, hatred, anger, fighting spirit, animosity or even bloodlust despite being in the midst of a battle against him, rendering it practically impossible for Muzan to detect him, predict his movements, or gauge how powerful he was with his senses. This gave Yoriichi an edge in battle against Muzan when he underestimated his strength, a mistake that haunted the Demon King for the rest of his life.
Extrasensory Perception: Outside of the sixth sense granted by the Transparent World which allowed him to see the inner workings of a person, Yoriichi also had extremely honed sensory abilities, able to detect things outside the normal range of perception. Like most high-level Demon Slayers, Yoriichi would be able to discern the aura of demons from humans while also be able to tell the strength of his enemies at a glance. During Yoriichi's first encounter with Muzan, he could immediately tell that, by destiny, he was born into this world to defeat him. Yoriichi was also able to accurately sense the Demon King's aura, which he describes as magma erupting from a volcano.
Unparalleled Swordsmanship: Yoriichi was the greatest swordsman to have ever lived. Even as a seven-year-old child with no training, he was capable of easily defeating a trained swordsman the very first time he ever picked up a sword, striking him in multiple areas across his body faster than the eye can process. His swordsmanship was so tremendous that a battle doll modelled after him had to be made with 6 arms wielding katanas and utilizing 108 techniques to even attempt to imitate Yoriichi's skills, and even then, the doll was still vastly inferior compared to him. His swordsmanship easily overwhelmed the Demon King, Muzan Kibutsuji, and he would have killed his twin brother, Kokushibo, the strongest swordsman in the current era, had he not died of old age.
From Akiko Yosano;
Thou Shalt Not Die: allows her to heal all external wounds as long as they are fatal or the person must be "half-dead". Due to this, her ability is inconvenient for healing minimal wounds since she needs to fatally injure that person first. Upon activating her ability, several butterflies appear to come out from her body and land in the surroundings. When touched by them, the injured will have their injuries healed instantly.
Combat Skills: Yosano is quite skilled in close combat, showing proficiency in wielding a large cleaver that she occasionally uses.
Physiology and Anatomy Knowledge: As a physician, Yosano knows when it comes to the human body, including the time it takes for the heart to fully stop and even stating which part of a corpse's body was affected when she rummages through different pictures of corpses from a brutal crime scene.