Naruto: Hashirama Is My Big Brother, but I'm Even Crazier

[No System!] [No transmigration] [Not a mindless power fantasy!] Senju Onima, the fifth son of the Senju Clan leader. He should have stood alongside his three older brothers to hold up the Senju Clan, but he could only watch as his third brother, Senju Kawarama, died before his eyes. In that moment, he understood one thing: in this Warring States era, where people kill people and clans wipe out clans, sunlight is a luxury, and weakness is a sin. Then a voice rang out in his mind. “Heh heh heh... Young man, do you crave power?” That power could let him fight Uchiha with the Sharingan head-on, and stop him from being the one who needed protection. But every time he used it, his body drifted a little further from his will. He was growing stronger, strong enough to make his enemies tremble. Yet Tobirama Senju watched him with growing wariness, and Hashirama Senju gripped his sword ever more tightly, because they could no longer tell whether the figure wearing that sickly smile on the battlefield was still their little brother. At the end of that mysterious voice, was there salvation, or a trap powerful enough to devour the entire Senju Clan?