Naruto: Passerby and Returnee

Main pairing: Sasuke and Naruto. Dual male leads, rebirth, no system, both protagonists are strong, both are strong, both are strong! Side pairings: Hashirama and Madara, Tobirama and Izumi, Ootengu and Kakashi, Itachi, etc. One day, future Naruto opens his eyes and finds himself lying on his old bed in his childhood home. Still shorter than a table, watch as the Seventh Hokage stirs up the ninja world and brings a different future. "I will liberate the whole world!" Serious story, main pairing slow-burn. Naruto's IQ is off the charts...