Nanashi Uchiha

was a kunoichi of the Uchiha clan during the Warring States Period. Because of Nanashi's extraordinary abilities, she was treated as nothing more than a weapon by her own clan and was always locked away in a cell, only being called out for battle. She was ultimately sealed away by the combined efforts of the Senju and Sarutobi clans. She was ultimately released almost a century later by Merz to be used as his tool for war, using Nanashi's hatred of shinobi and the world alike to gain her trust.

Background
Nanashi was born as "Hikari Uchiha" by her parents, who wished her to live her life in the sunshine as much as possible, hence her birthname. However, her parents were killed at some point during the vicious war-torn Warring States Period, leaving her orphaned. Once her fellow Uchiha clan members discovered Nanashi's powerful abilities, they decided to use her as a weapon for battle, telling her only purpose was to serve them in battle, and gave her the name "Nanashi" to signify her lack of identity as a human being. For several years, Nanashi was kept locked away by her own clansmen, being treated as a weapon, often being referred only as "it" by others. Ultimately, however, during a battle against the Senju clan, Nanashi's power forced them to retreat, only for them to return with assistance from the Sarutobi clan, who managed to defeat the Uchiha and seal Nanashi away in a scroll, preventing her from being used again for battle.

Nanashi remained sealed away for over nearly a century, up until she was released from captivity by Marz, who used Nanashi's hatred for shinobi and the world alike to make sway her to his side, promising to help Nanashi get her revenge by plunging the world into chaos, and with her hatred being extremely deep, she accepted his offer, and as such, began working with his Zero organization to destroy the world by bringing the Five Great Shinobi Countries into war. When Boruto's traveled back in time to the Warring States Period with the help of Toneri Ōtsutsuki, Nanashi's history was changed when Boruto rescued her from captivity, and after informing her about her real name given to her by her parents and urging to live her life the way she wanted, Nanashi was able to live a modest and normal life away from war, and spent the rest of her life in gratitude to Boruto, even leaving an anecdote behind sharing how much Boruto changed her life for the better.

Personality
Because of the extreme mistreatment she suffered at the hands of her own clan, being treated as nothing more than a weapon, not even being referred to as a human being, but only as an object, Nanashi developed a deep hate for not only her own clan, but shinobi as a whole, along with reality itself. As a result, Nanashi eagerly accepted Merz's offer to bring chaos to the world in order to gain her revenge upon shinobi. However, upon meeting Boruto Uzumaki in the virtual game world she created, Nanashi began having conflicting feelings; while initially annoyed with Boruto's persistance to talk to her and impress her, she gradually found him interesting and different from others, who only talked to her as part of her duties as a "guide" for the game, whereas Boruto genuinely wished to become her friend.

At the same time, however, Nanashi still struggled to let go of her hatred, and began suffering from great emotional turmoil over her feelings of hate against her feelings of joy regarding Boruto, but still went ahead with her plans, although she unknowingly caused herself great harm as she subconsciously wished to keep Boruto safe from her own plans. When clashing against Boruto, Nanashi was unable to bring herself to kill him, shedding tears and pleading for Boruto to stay away, but due to Boruto's unwavering determination to rescue her from her hatred, she ultimately came to accept his feelings and granted him her chakra to help defeat Merz, although at the cost of her own life. After Boruto traveled back in time to the Warring States Period with the help of Toneri Ōtsutsuki, Nanashi was once again saved by Boruto, this time from her own clan, and after seeing just how Boruto was determined to save her, and hearing his words about choosing her own path instead of accepting one made from others, she decided to live the rest of her life unaligned with any clan, and with her birthname returned to her by Boruto, she lived a modest life surrounded by people who cherished her, and while refusing to speak about her tragic past, Nanashi would only, and happily, talk about meeting Boruto and how her life was influenced by him, leaving an anecdote behind, thanking him for changing her life for the better.

Trivia

 * means "nameless".