TV-Series
Description
Jett-senpai is a central supporting character in the anime Star Detective Precure!. He is a fairy who typically appears as a human boy and serves as the tech support and mentor-like figure for the main heroines.

In his true fairy form, Jett is a cream yellow cat-like creature with shamrock green eyes, pink inner ears, and distinctive heart-shaped patches on his cheeks. He also wears a pair of goggles. However, he is deeply embarrassed by this form and prefers to stay in his human disguise. As a human, he is depicted as a boy with messy yellow hair tied into a ponytail, retaining his green eyes and goggles. His outfit consists of a dark teal hoodie, purple shorts, a long white lab coat, white socks, and yellow sneakers.

Jett has a self-proclaimed title as a genius inventor and scientist, having originally come from the CUREtto Detective Agency's London branch. He traveled to the agency in Japan with the intention of closing the office, as the previous Cure had left months prior. Despite his genius persona, he has a kind and caring personality and is genuinely good at looking after others. He can be blunt and is very proud of his talents, which sometimes comes across as arrogance, but he is also hardworking and deeply supportive. He has a notable fondness for candy and other sweet things.

His role in the story is established early on when he meets the protagonist Anna and her companion Mikuru. Initially doubtful of their abilities as Cures, he is convinced after witnessing them fight against the villain Nijee. Following this, he officially welcomes them to the agency and provides them with the PreKit Book and Pen to register as official Star Detective Precure. He becomes a crucial ally, using his inventions, known as Pre-Kit, to support the girls in their investigations and battles. He acts as a grounding presence at the detective agency, offering a place for Anna to stay when she finds herself stranded in the past and providing guidance. For instance, he encourages Anna when she is unsure of herself, telling her that she and Mikuru form a miraculous pair.

Jett's key relationships are primarily with the two main Cures, Anna and Mikuru. They admire him and refer to him with the affectionate honorific -senpai. He is a source of wisdom and practical support, often investigating the mysteries surrounding the magical items the girls use. A significant part of his background involves his grandmother fairy, Shinian. From her, he learned the importance of making inventions that are not only functional but also cute and appealing, a lesson that contrasts with his earlier belief that functionality was the most important aspect. His treasured goggles, a gift from Shinian upon his graduation from her workshop, are a prized possession, and he is known to chant a charm she taught him, Puri Puri, Pretty Smile.

In terms of notable abilities, Jett is a prolific inventor. He creates various devices to aid the Star Detective Precure, including communication badges and the PreKit items they use to transform and fight. His inventions are a key part of the team's operations, enabling them to solve mysteries across different locations. He is also, despite his embarrassment, a fairy with an extraordinarily long lifespan, claiming to be 222 years old.