Saori Hidaka is a member of DJ unit Merm4id. Inspired by a remix from someone connected to club FROLIC, she began her DJ career in high school. Despite developing considerable technical skill through hard work, her pessimistic outlook initially kept her from actively pursuing DJing even at university. Rika eventually persuaded her to join Merm4id, a decision that motivated Saori to change her mentality and work towards her goals.

Before joining Merm4id, Saori described herself as a deeply pessimistic loner who struggled to make friends and often did activities alone. This social difficulty extended to her part-time jobs, where trouble getting along with coworkers led her to quit. Within Merm4id, she frequently acts as the straight man, tempering the antics of fellow members Rika and Marika to prevent situations from escalating, such as intervening when they dote excessively on another member.

A collaboration event with an American DJ and producer triggered a severe depressive episode for Saori due to her insecurities about musical abilities and the pressure of learning English. Despite the emotional turmoil, she mobilized her efforts to resolve the situation, aided by support from her unit members.

Saori enjoys reading manga, light novels, and regular novels. Her hobbies include calligraphy, playing retro games, browsing the internet, and lying down on the floor. She has a strong affinity for pandas and dislikes cilantro, citing jealousy over how it stands out. Her favorite foods include delicacies, offal hot pot, ramen after drinking, cheese, squid, scallops, nuts, cucumbers, octopus, and shark cartilage. She harbors a fear of insects and is notably ticklish, a trait other members exploit to alleviate her anxiety before performances.

Physically, Saori has wavy, short purple hair with bangs nearly reaching her shoulders and light teal or turquoise eyes. She stands 161 cm tall.