Akiko Irie is Shoichi's older sister.
Akiko looks quite different from her brother. She has long, dark hair which she wears in pigtails, and was seen wearing a sleeveless polka-dot shirt in the manga.
She has a personality with a dry sense of humor.
Not much is known about her but it is known that she recently had a boyfriend.
She had a minor role in Shoichi's first appearance during the Daily Life Arc. Both Akiko and their mother Tomoko were seen urging Shoichi to handle the Ten Year Bazooka, saying it was a man's responsibility. Akiko then replaced Tomoko at some point during a phone conversation with Shoichi because Tomoko didn't understand what Shoichi was trying to say, and went shopping.