Mahiru is an optimistic and sensible girl who is generally rather calm and unafraid to speak her mind. She initially comes off as confident, but is later revealed to have self-esteem issues. Mahiru compares her photographs to those of her mother, a famous war photographer whose career led her to be absent from home for much of Mahiru's life. Her father was a very poor parent, leaving the responsibility of the housework entirely to her. When Hajime Hinata was being scolded by Mahiru, he likened it to being yelled at by his mom.

Mahiru has high expectations of men and is quick to be abrasive towards them. She is much more tolerant and friendly to girls. The subjects of her photos are usually of girls and explains that she easily gets bored of photographing guys. She loves taking photos of people's smiles, and it's revealed in her Free Time Events that she recorded everything in the island so that they won't forget, except for the guys which she only recorded once every three days. Despite her love for photography, Mahiru believes her title is stupid compared to her classmates. She has been shown to dislike selfies.

Mahiru wants to help as many people as she can, but it'd be a mistake to call her a pushover. She doesn't hesitate to scold those who are rude to her and is also really good at taking care of people although never failing to complain about it. Mahiru is introduced as people-hater who lack manners, though she later develops a very close friendship with Hiyoko Saionji. Because Mahiru is a reliable person who thinks of her friends and is prone to taking care of people, she has many friends outside of her own class as well.