Rion is a spirited and free-spirited individual who lives life on her own terms. Because of such a nature, she often disregarding the consequences of her actions. She also demonstrates a strong sense of responsibility toward others and protected them. She is compassionate and altruistic despite her reckless nature as an assassin. Rion is a very warm and friendly person Rion is a tall, attractive and slim young woman with turquoise shoulder-length hair and yellow eyes with white pupils. She is 17 years old. She is often seen wearing a white tank top with a partially zipped, off-shoulder black jacket and a pair of black pants along with black shoes. Rion is the aunt of Akira Akao, having taught her how to see the "paths" which lead to a person's death(imaginary lines representing future actions she can take to kill a particular target.) She can maintain intense combat sessions for up to nine hours straight without breaking. She speaks her mind without elegance, has no grand ambitions to change society (finding such thoughts boring), and enjoys everyday vices like heavy smoking.

Yoichi Nagumo is a current friend of Sakamoto, Rion, and Guest. He is a charismatic, playful, and deceptive assassin, often toying with his opponents before delivering a fatal blow. He is 17 years old. Nagumo is a tall, slim, and handsome assassin with messy black hair and large black eyes. Nagumo is considered "filthy rich". Hailing from a famous family of spies, he reportedly lives alone and owns a large luxurious mansion in a private, wealthy neighborhood.

Taro Sakamoto is a calm, stoic, and good-natured man of few words who lets his actions speak for him. Sakamoto's appearance features a tall, lean, and a sharply chiseled build. He is widely noted as very handsome, drawing large crowds of female admirers and Valentine's gifts. He is 17 years old. Sakamoto is very callous and indifferent to killing, being described as the perfect killing machine who felt absolutely no emotion when taking on a job.