Sairenji Akiho

Akiho Sairenji is Haruna's older sister. Due to their parents moving away, Haruna decided to stay living with her older sister in her apartment instead. It has not been specified what she does to support herself and Haruna, but in Darkness Chapter 18, she mentions her boss being "editor in chief".

Appearance
Akiho is a reasonably tall and highly attractive woman with long purple hair and eyes. The shape of her face and eyes bare some resemblence to those of her younger sister Haruna though she is taller and more curvasious.

Personality
Akiho is very mature, though in an adult-like way, and she is a casual dater. She enjoys dating boys, but has no desire for a serious relationship, and only intends to "play with them for a while".

She is extremely popular with the guys (having received confessions from two men at the same time), but continuously turns them down, as her sister states she is not looking for love at the moment. She has been dating Yuu Kotegawa, though she isn't taking the relationship seriously.

Haruna Sairenji
Her little sister who she occasionally would enjoys teasing over certain things like having friends over and mentioning embarrassing stuff to them, which Haruna greatly dislikes, although they do get along closely. She is aware of Haruna's romantic feelings for Rito and is "gleefully" supportive of them.

Yuu Kotegawa
Yuu is someone Akiho is currently dating, but she isn't taking it as seriously as he does. Sometimes he would call to ask her out again, but she would decline with a dishonest excuse. It is unknown if they are still together.

Maron
Maron is basically her pet dog, but since she is often at work, her sister Haruna is always the one taking care of him.

Trivia

 * The word "Aki" (Kanji: 秋) in her name means Autumn.
 * With the debut of Haruna's parents in the Darkness Chapter 54, the whole Sairenji family will make up the four seasons of a year: Haru in Haruna is of Spring; Natsu in Natsumi is of Summer; Aki in Akiho is of Autumn (Fall); and finally, Fuyu in Fuyuhiko is of Winter, thus complete the cycle.