Atsui

is a shinobi from Kumogakure.

Personality
In stark contrast to his elder sister Samui, Atsui has a rather hot-headed and spirited attitude, which is evident even in battle. He prefers attacking his enemies head on, leaving him entirely devoid of any support at times. He has a tendency of saying the word and admits that he has created a substantial amount of "hot-shot" catchphrases.

Appearance
He has neck-length, blond hair, worn in an asymmetrical bowl cut style and green eyes. His typical attire consists of a sleeveless version of the standard Kumogakure uniform, along with the village's respective flak jacket. He also has bandages on his forearms, shin guards and the kanji for tattooed on his left shoulder.

Kenjutsu
Like many other Kumogakure shinobi, Atsui is extremely proficient in kenjutsu, and incorporates a long, white-hilted katana as part of his main fighting style. When this blade is utilised in conjunction with his Fire Release nature transformation techniques through the application of Chakra Flow, he becomes capable of incinerating a significant quantity of opponents in an instant. The anime also showed that he is able to conjure flames with each swing of his sword.

Fourth Shinobi World War: Confrontation
Atsui, along with his sister were assigned to the First Division of the Allied Shinobi Forces during the Fourth Shinobi World War. When Darui confronted the reincarnated Gold and Silver Brothers, Atsui and his sister provided assistance. Attacked almost immediately by numerous White Zetsu Army clones, he incinerated them before he moved to confronted towards the opposing Kinkaku and Ginkaku head-on. Both he and Samui are hit by the Kōkinjō, resulting in their being drawn from their bodies.

With their respective word souls subsequently severed by the Shichiseiken and absorbed by the Benihisago, the siblings are placed under a combination curse and sealing technique, where if they uttered the word they've used most in their lives, they'll be imprisoned for eternity. Although Samui advised that he not speak, Kinkaku's subsequent attack prompted Atsui to say "hot", causing him to be sucked into the gourd. Darui later promised to find a way to release him and Samui who was sucked into the gourd as well. The gourd with Atsui and Samui inside was later taken by Tobi in order to seal the portion of the Nine-Tails' chakra that was within Ginkaku who was also absorbed into the gourd some time later.

Kaguya Ōtsutsuki Strikes
After the conclusion of the war, he and his sister were finally freed from the Benihisago by Darui.

Trivia

 * means "hot" in Japanese (in reference to temperature), in contrast to Samui's name which means "cold".
 * Aside from Team Kakashi, Atsui and Samui were the only members of the Allied Shinobi Forces to not be affected by the Infinite Tsukuyomi.

Quotes

 * (To Samui) "Looks like you're a little hot under the collar today, sis! These guys must be something else!"
 * (To Darui and Samui) "They look like nasty weapons, but in the end they're just tools! Our techniques have soul, they're too hot for these guys to handle!"
 * (About his most used word) "What could it be? I've got a million hot-shot catchphrases, but which one do I use the most? Which one is it?!"