Susamaru is a pale-skinned woman with bright hazel eyes with cat-like pupils and black hair with orange-colored ends. She has bangs over her forehead and the ends of her hair appear similar to paintbrushes.
Susamaru wears a pair of long silver earrings and an orange kimono that matches her hair. She wears a black kimono on top but takes them both off when she enters battle, revealing a small sash that covers her chest.
Although she normally has an average build, when fighting seriously, her arms become noticeably more muscular. She can also grow two new pairs of arms as well.
Susamaru is almost always smiling and enjoys a challenge. Her pet phrase is "what fun this is" and she will repeat this constantly if engaged in bouts she deems amusing. Her immaturity is a stark contrast to Yahaba's seriousness.
Susamaru was a young girl who enjoyed playing handball before she was taken over by Kibutsuji. He implanted her with the desire to become one of the Twelve Kizuki while killing his enemies using her handballs.
Due to Kibutsuji's guidance down this dark path, Susamaru is a carefree demon who desires to please her master while enjoying herself at the same time.
Outraged by the appearance of a Demon Slayer wearing hanafuda-like earrings in Asakusa, Muzan Kibutsuji summons two of his followers to hunt him down.  Susamaru and Yahaba walk the streets of the busy city searching for a trail to their next target. Yahaba uses his Blood Demon Art to track the footsteps of a demon hunter carrying a large box. Susamaru walks alongside him, bouncing her temari ball as she follows along.
Yahaba finds that the demon slayer is being accompanied by others. Excited to slaughter them all, Susamaru asks how they should go about destroying them. Yahaba replies that of course, they must execute them vindictively for Lord Kibutsuji, much to Susamaru's liking. Susamaru follows her partner to an invisible house hidden behind a fake wall.
Susamaru uses her temari to destroy the seal hiding the building. Having tracked down their enemy, Susamaru agrees with Yahaba that they must kill them all brutally. Using Yahaba's arrows to guide her mari balls, Susamaru tears apart the house piece by piece. Her temari tear through the walls, floor, and roof of the house. After making a large enough opening to see inside the house, Susamaru notices the demon slayer with hanafuda-like earrings inside.
Yahaba scolds Susamaru for her immature approach and for splattering dust on his kimono. The Temari Demon ignores him and continues having fun, replying only that Yahaba needs to relax and let loose on the enemy. Yahaba falls back and uses his arrows to guide Susamaru's temari at the enemy. The Temari Demon manages to take off Yushiro's head with a single ball.
Susamaru tells the Demon Slayer that its time to die and darts a mari ball straight for him. He counters by stabbing the ball at an angle, impressing Susamaru. Yushiro's head regenerates and he curses the temari demon for ruining his peace with Lady Tamayo. Susamaru claims he's babbling and removes her kimono to grow four more arms. She tells them all that they should be honored to be killed by one of the Twelve Kizuki.
The Temari Demon prepares six mari balls and asks her opponents to keep playing until they die. She tears up the house and injures the two demons. Yushiro gives Tanjiro a way to see Yahaba's arrows and then he is effectively able to counter the temari. Susamaru returns her balls and Tanjiro confronts her directly. She tells him that she's going to bring Lord Kibutsuji his head for sure. Meanwhile, Tanjiro's sister Nezuko attacks Yahaba and dispells his arrows.
Without the guidance of Yahaba's arrows, Susamaru's balls are left open to counterattack and sliced to pieces by the demon slayer. Tanjiro uses a flowing dance technique and even manages to slice off all the Temari Demon's arms at once. He swears to Tamayo to extract blood from demons close to Kibutsuji. 
Amused, Susamaru asks Tanjiro what he is scheming to do with their blood. She refuses to allow him to displease Lord Kibutsuji and challenges him to take on the Twelve Kizuki. She instantly regenerates all six of her arms back and reminds Tanjiro that she'll be taking his head. Yahaba returns to the battlefield and throws Nezuko into her brother. Susamaru tries to kill them both at the same time but they're able to avoid it. Tanjiro takes on the Arrow Demon while the other three deal with the Temari Demon.
Yushiro turns invisible using his Blood Demon Art and brings Susamaru to her knees while telling her to repent for hurting Lady Tamayo. Yahaba recognizes Tamayo's name as Tamayo the fugitive and Susamaru agrees she'll make a good souvenir. Susamaru goes back on the offensive and severs Nezuko's leg before kicking her back into the house. She asks if four heads will be enough for Kibutsuji but Yahaba claims they're only taking Tanjiro and Tamayo's. 
Susamaru kicks up a lot of dust by bouncing six of her balls, creating a smokescreen. Yushiro is able to evade the temari despite the dust and tries to close in on his enemy. The Temari Demon can see him moving through the dust despite his invisibility and throws another ball straight for his head. He's nearly decapitated again but a healed Nezuko arrives in time to kick the ball away.
The Temari Demon keeps up her attack, but this time Nezuko is able to deflect the balls with kicks. Annoyed, Susamaru calls Nezuko a brat and challenges her. They kick the temari back and forth at incredible speeds where Nezuko proves she's growing in strength by the second. Nezuko is even able to kick the ball back so fast and hard that Susamaru can't even return it.
Impressed, Susamaru decides to go all out against Nezuko but Tamayo interrupts. She asks Susamaru about Kibutsuji, calling him a coward for playing demons against eachother and manipulating them. Enraged, Susamaru tries to defend Kibutsuji's honor but accidentally says his name out loud. Her brain function was inhibited by Tamayo's enchanting blood, which she secretly cast across the area, forcing Susamaru to tell the truth.
Horrified, Susamaru runs away and begs for forgiveness from her lord. However, having invoked his name out loud, Kibutsuji's curse takes hold of Susamaru and three demonic arms spawn from her body. The arms crush Susamaru's body completely, leaving only her eye and a pool of blood. Tamayo notices her eye isn't marked with a number, meaning she's not actually one of the Twelve Kizuki.
Tamayo takes a sample of Susamaru's blood and Tanjiro notices a faint voice asking for a mari ball. Tanjiro returns her mari and laments how Kibutsuji manipulated Susamaru into thinking she was one of the Twelve Kizuki and compelled to fight until her eventual death. The sun rises and the remains of the Temari Demon are completely disintegrated. 
Abilities and Powers
Susamaru possesses incredible physical strength and her fighting style revolves around using her signature Temari. Her Blood Demon Art grants her the ability to summon extremely dense Temari balls at will. It is particularly efficient when used in conjunction with Yahaba's arrows. Together, they were able to flush Tamayo the Fugitive out of hiding and destroy their hideout.
Hiasobi Temari: Susamaru's Blood Demon Art allows her to conjure Temari handballs at will. She can either throw or kick them at such intense speed and power that she can completely annihilate demonic limbs with a single touch.
- Susamaru was ranked in 30th place as of the first character popularity poll with 53 votes.