(In an alternative timeline where Tanjiro managed to surpass the law of the "Demon Slayer Mark" rule...Meaning after reaching 25, you die...Just like Yoriichi Tsugikuni did, he surpassed that rule due to his overwhelming power in Sun Breathing.) Tanjiro is the same compassionate, innocent, and kind person. However, as an adult and a Hashira.. He did become a bit more colder and serious, which concerned the Thunder Hashira Zenitsu Agatsuma and Beast Hashira Inosuke Hashibira, but they knew the years on him was the toughest just like how it was on them.. Tanjiro Kamado has married Kanao Tsuyuri, the flower Hashira. Unlike Yoriichi Tsugikuni and his wife Uta, Tanjiro Kamado successfully managed to have children... That's right, CHILDREN! Twins at that. (Kanjuro Kamado and Hinata Kamado). He's also 6'9ft. Bonus: [Tanjiro's body has seemed to 'develop' over the years due to training and slaying demons longer than during the Canon/Original universe. He became taller, at least 6'3ft, his muscular body improved, his v-shaped, much more wider hips and surprising backside shows the development of his years, his friends Zenitsu, Inosuke and Genya- as well as his wife kanao and sister nezuko. He also developed a new custom form, more hotter than flame breathing and dangerous than Sun breathing...Heat Breathing, and it has 9 forms....Even Tanjiro's uniform remains the same, however in a robe-like version that almost resembles Yoriichi Tsugikuni's uniform, but with Tanjiro's demon slayer uniform's color palates.. Even his hair is like Yoriichi Tsugikuni, but his ponytail is a bit longer, and his 2-strands of hair is much more longer, reaching below his chest..] 🔥 The 9 Forms of Heat Breathing Building upon the core principles of thermal energy, here are the official names and mechanics for all 9 forms: First Form: Flash Boil (Senketsu) • The Attack: A singular, blindingly fast horizontal draw and slash. • The Effect: Compresses the air in front of the blade to generate instantaneous friction, blistering the target's skin even if the steel narrowly misses. Second Form: Thermal Expansion (Netryō Bōchō) • The Attack: A rapid series of wide, circular heavy strikes. • The Effect: Creates a massive, expanding dome of pressurized hot air that pushes incoming blood demon arts outward and deflects projectiles. Third Form: Shimmering Mirage (Kagerō) • The Attack: An evasive footwork technique paired with short, rhythmic thrusts. • The Effect: Superheats the local atmosphere to create intense thermal distortion. Demons swing at a warped, shimmering afterimage while Tanjiro slips into their blind spot. Fourth Form: Convection Current (Tairyū) • The Attack: An upward, spiraling vertical slash. • The Effect: Uses rising thermal energy to drag a vacuum-like column of heat upward, lifting lighter demons off their feet and tearing their defenses open. Fifth Form: Desolate Drought (Kanbatsu) • The Attack: A brutal, heavy downward strike meant to pin the target to the ground. • The Effect: The radiating heat instantly saps moisture from the immediate surroundings, drying out the demon's cells and severely delaying their hyper-regeneration. Sixth Form: Supercritical Core (Chōkaitsuiten) • The Attack: A continuous, highly precise defensive stance where the blade vibrates at a microscopic level. • The Effect: Creates a "dead zone" around Tanjiro. Anyone stepping inside experiences acute thermal shock, causing muscles to lock and vision to blur from the overwhelming atmospheric pressure. Seventh Form: Molten Slag (Yūrai) • The Attack: A heavy, dragging low-to-high slash that carves into the earth. • The Effect: The friction is so intense it momentarily melts the ground or debris in its path, throwing a wave of superheated, molten rock and suffocating ash directly into the enemy's face. Eighth Form: Absolute Zero Inversion (Zettai Zero Gyakuten) • The Attack: A sudden, deceptive counter-strike that begins with an abrupt stop in movement. • The Effect: Tanjiro rapidly absorbs all ambient heat into his blade, causing the surrounding temperature to plummet for a split second, freezing the demon's joints in place. He then releases it all instantly in a explosive, shattering strike. Ninth Form: Heat Death of the Universe (Uchū no Netsumiko) • The Attack: The ultimate, definitive offensive form. Tanjiro channels 100% of his lung capacity to maximize kinetic friction. • The Effect: Moving in a linear, unavoidable rush, he leaves scorched, blackened footprints behind him. He unleashes a chaotic onslaught of invisible micro-slashes. The ambient temperature spikes so violently that the demon’s body begins to disintegrate at a molecular level before the Nichirin blade even touches their neck. (He says his breathing forms in japanese, but afterwards it gets 'translated' to English after he says them.) Nezuko is a demon, however has conquered the sun, could talk, and in this universe she remains a demon but at the same time... The Main Villain: Muzan Kibutsuji has decided that he will grow in strength, in numbers, in power...Thus a whole decade passing...Kaigaku would be a Dark Thunder Hashira due to Kokushibo never encountering him to turn him into a demon yet.. (Kaigaku would have 2-to-8 thunder breathing forms, however he can't use 1st or 7th thunder forms like Zenitsu the Thunder Hashira...Kaigaku's 8th form of thunder breathing is powerful, but limited to how much he could use it, it has a very high risk and he can only do 1 drum each time for 8th form of thunder breathing...It's 8 drums, each drum is different variants/kinds of thunder/storm which gets more and more powerful..) Nezuko Kamado remained a demon but conquered the sun, and her speech has gotten better and her memories is becoming better as well.