The new demon king (Completed)

Jōgen no Ichi

When the water hashira tomioka Giyuu, was believed to be dead after the previous attack of Arata, Uppermoon 1. He had a dream, he was in his mindscape and had a vision, there he was back at his old home, his old estate in his previous life, and there he was eating with the very same person who made him smile, after Sabito and Makamo.  Tanjiro. 

"Is this how I die?" Giyuu asked himself, his arm was gone, he was bleeding out, too wounded to move, out of energy. "At least, it will be peaceful... Tanjiro, I am sorry I wasn't able to  save you before,  seems like I won't be able to save you now."

He closes his eyes, embracing his death till he heard an all to familiar voice "Now isn't the time to die Tomioka-san!" His eyes shot open as he saw a boy with long crimson hair tied to a high ponytail and a green and black checkered haori. 

"Get up! Kanae-san, Obanai-san needs you now!" 

"Tanjiro?" Giyuu couldn't believe what he was seeing nor hearing, tears swell up in his eyes. 

"You cannot die now! Get up! You are Tomioka Giyuu! And the Water Hashira! You protected so many innocent lives, you have come so far not to just die now!" Tanjiro said before vanishing. 

Giyuu stands up, grabs his blade with his one arm, and mutters to himself "I'm sorry Tanjiro, sorry I was going to give up so soon! I am the water hashira!" 

The demon mark awakens as he swiftly runs back to the battlefield. In the distance, he sees Shinobu die, he wanted to cry, but not now! Shinobu's death cannot and will not be in vein. 

"Breath of water, Fourth Form: Striking Tide, Turbulent" An improved version of the Fourth Form: Striking Tide. The user increases the quantity of consecutive strikes and slashes along with improving its accuracy in order to contact a specific target during a chaotic situation.

He parries and slashes Arata's attacks, pushing her back, saving Kanae, he had made a promise to Shinobu, to protect her sister like she protected her, and he shall keep his promise even if it shall cost him his life. 

Arata sees the demon mark on Tomioka Giyuu, infuriating her. He does not deserve it, he should not get it, how dare he. "You do not deserve that demon mark, you think you deserve the power, the strength of the demon mark? You could not protect those who were close to you!" Arata yelled while pointing her blade towards him. 

"Oh I know of your past life, even with the demon mark you couldn't protect the one closes to you." She taunted "But enough talk, show me your new found strength, Hashira." 

He grits his teeth, but calms down. He cannot let his rage cloud  his judgement, even with the demon mark, they can't reach level, she was in her own league unlike the uppermoons. She even had a demon mark of her own, the veins or vines that come out of her eyes. 

Giyuu jumps high into the air "Breath of water, Eighth Form: Waterfall Basin"  The user cuts the target vertically in a flowing motion which is most effective when they are falling downward.

"Breath of blood, Seventh Form: Vengeance." Arata performs a series of powerful sword slashes that seemingly takes the form of a red wolf 

Both attacks intercept but Giyuu was thrusted back due to his grip on his sword, pretty hard to fight with just a single arm. Arata eyes locked onto Giyuus, but breaks eye contact as she sees a giant white snake behind her. 

"Breath of blood, Thirteenth Form: Brutal Anarchy." Arata creates a long-ranged triple-layered slash twister. The twister parries the white snake away but seeing as she is given no time to even scan her surroundings, she swiftly turns to the left to see the incoming flower hashira.