Haruka Sawaguchi (沢口 遥, Sawaguchi Haruka) is one of Teru Kurebayashi and Kiyoshi Hasegawa's classmates and friends, who often acts as the leader of sorts in Teru's group of friends. She encourages Teru's relationship with Tasuku Kurosaki with sincerity and humour, being generally unafraid to say things that Teru is too embarrassed to admit. She is the first friend that Teru confides in with her knowledge that she is aware that Kurosaki and DAISY are the same person.
Haruka is frequently the first to come to Teru's defense at school, often leading their other friends to join suit. She is a member of the school's art club, track team, and ghost club. Unlike Teru and Kiyoshi, she comes from a well-off family with some connections.