SI Tenten who was a weapon researcher in her last life.
Have her be the daughter of a blacksmith in Konoha. She starts learning fuinjutsu to develop various Shinobi tools for herself. She can find the gelal stones for powering her tools.
Personality : Otaku
Main chakra nature: Fire
Suggestions for tools: Ninjutsu storage and absorption (ideally 3-4 A-rank jutsus as the capability), beyblade for creating tornados to combine with her fire release jutsu, grenades(paper bombs, but more effective using real explosive powder), guns(debatable).
Strength during the war arc: Jonin. Sniping Obito at the perfect timing, Madara dodging the bullets and going after her, to be saved by Neji.
Love Interest: Neji