Susuru Kojima is a shy and nervous boy (think Chihiro Fujisaki), and pushes people away out of fear of them disappointing him (like others have done in past relationships), but does so gently. He works at a small Fix-it shop with father but a dramatic incident that got his talent recognized.
Susuru has a distinct love for machines and he finds himself most at home in his workshop working on his gizmos and gadgets. Despite his ingenuity, Susuru is very humble about his abilities, often downplaying them, and doesn't consider himself to be the Ultimate Engineer. However, he is wrong in this regard as he has yet to discover his true potential.
(Susuru possess a childish voice despite his mechanical skill so try to voice him within those lines. Essentially an expy Miles Prower of the Sonic Franchise)