Page "Ultraman Tiga" Paragraph 38

: A world class top scientist.

He is also a descendant of the ancient race, like Daigo, and bears similar DNA.

He found another Ultraman statue in Kumamoto, similar to the ones that Tiga was imprisoned as.

Masaki feels he has just as much right as Daigo to inherit the light and transcend his humanity to become god-like but the only thing he lacks is a transformation item, like Daigo's Spark Lens, to allow him to transform into the Ultraman.

To prepare himself for what he feels is his birthright, Masaki has trained his body to be strong and powerful, and physically worthy of being an Ultraman.

Masaki feels Daigo does not deserve the monopoly he has on the light, so Masaki beats an exhausted Daigo, who just defeated Geoshark, and thus acquires the transformation item he lacks.

A stray dog leads Daigo to Masaki's base in a cavern, but Daigo is unable to talk Masaki out of it.

Masaki places the stolen Spark Lens in a converter, which is protected by an electric barrier, changing his body into light particle and merging with the Ultraman statue.

However he lacks the heart and has greedy and selfish intention, thus corrupting the new giant of light into a giant of darkness, Evil Tiga, and causing him to start rampaging into the city.

Ultimately, Daigo able to recover the Spark Lens as he forces himself to endure the electricity and is able to break through by force of will to the Spark Lens.

After a bitter fight, Tiga gains the upper hand and wounds Evil Tiga enough that he can fire his Zepellion Beam, vaporising his corrupted counterpart.

While sharing most of Tiga's powers, Evil Tiga also shared his weakness of only being able to remain on Earth for a certain period of time.

Its unknown if Evil Tiga can switch forms like Tiga can, due to the short period of time in which he appeared.

While Evil Tiga was destroyed, Keigo survived and was captured by authorities.

In the end of the series, Keigo returned to help GUTS revive Ultraman Tiga after his defeat at Gatanozoa's hands, in order to redem his misdeeds.

While GUTS kept Gatanozoa busy, Keigo went down in a submarine and used a beam of light in an attempt to revive the hero and while Gatanozoa stopped him, Keigo's attempt revived Daigo deep inside the statue, allowing him to see the children of the world call out to him and use their light to revive Tiga as Glitter Tiga.