| This article, Tsuyoshi, is property of Omnikaiser. |
| colspan="2" style="border-top-left-radius: 7px;border-top-right-radius: 7px;border-bottom-left-radius: 7px;border-bottom-right-radius: 7px; text-align:center; font-size:13.5px; font-weight:bold; background:#000000; color:#003844" | Tsuyoshi | |
Current | Child
 | |
| Name | Tsuyoshi |
| Kanji | 毅 |
| Romanji | Tsuyoshi |
| Birthdate | June 16 |
| Age | 2000 + |
| Gender | Male |
| Height | 180 cm |
| Weight | 72 kgs |
| Blood Type | AB- |
| Hometown | Unknown |
| Home Country | Unknown |
| Affiliation | Himself |
| Previous Affiliation | Himself |
| Team | None |
| Classification | S-Rank |
| Nature Type |  Lightning Release |
| Jutsu | Capturing the Human Heart Technique Fūinjutsu Transfer Medium Spiritual Transmigration Segaki Creation of All Things |
| Weapons | Kunai Shuriken Sword Fūinsha |
Tsuyoshi is an ancient shinobi who lived at the time of the Sage of the Six Paths thousands of years ago. He was a citizen in a small village. The Sage came to the mentioned village in order to spread his knowledge of Ninshū and to bestow some of his legendary artistry upon the citizens of the village. Tsuyoshi was eight years old when the sage came to the village. All the people in the village learned Ninshū and began practicing it. Ninshū is the art of control over the spiritual energy. It was the base for developing Ninjutsu, which is used by shinobi nowadays. Ninshū is a forgotten art. Tsuyoshi grew in that village with the citizens who learned Ninshū and he learned it from them. As a kid, he showed great talent in using Ninshū. Growing up, as the world collapsed and war began to enrage everywhere in the world. Ninjutsu was developed. Ninjutsu is an application of chakra just like Ninshū. However, Ninjutsu was used for harmful reasons and killing purposes. It was created for that sole reason.
After developing Ninjutsu, people began to abandon Ninshū and learn Ninjutsu seeking the power that lies within it. On the other hand, Tsuyoshi never forgot about Ninshū, despite learning Ninjutsu himself. He resumed his training and developing of Ninshū. Seeing the changing of the world after the creation of Ninjutsu, he vowed to protect this world as long as he lived. However, he realized that the life of humans are limited as they last a relatively short period of time. That encouraged him to develop a Ninshū to counter the effects of aging in order to have eternal youth. He called this Ninshū "Spiritual Transmigration". This technique helped him overcome the effects of aging and the weaknesses of the human body giving him a form of immortality. As for his spiritual energy, he used a Ninshū called "Segaki" in order to take the souls of others to refresh his own. With these Ninshū, Tsuyoshi was granted immortality. However, immortality was not what he desired. He desired peace. He promised himself that he will refrain from using those two Ninshū and let his body die if the world returned to the peace that it was in during ancient times. If it didn't, then he would seek out that peace until he finds it. He made it his goal to be the savior of the world.
Tsuyoshi's true identity is an enigma for people. they don't even know that he exists. He studies people and tries to understand them and relate to them by living amongst them. After he takes someone's body, he lives his life and spend time in his village to understand people. Tsuyoshi roamed the whole shinobi world, taking many identities and many names. No one knows his true identity except a hand full of people.