Haruka Hoshi is a Time Lease scientist applying her technical expertise inventing essential gadgets and mechanical solutions for the team's missions. She pilots the organization's time-traveling vessel and contributes to the operation and maintenance of the primary mecha unit, Gyakuten-oh.

Analytical and creative, she develops vital solutions under pressure. Haruka exhibits a hands-on approach, readily joining field operations and confrontations when necessary. This practicality complements her strong loyalty to colleagues and organizational objectives, while her dedication to protecting historical integrity drives her actions.