Events during Nizetti's past are unknown, although Valna seems to have met him sometime before the third game. When Valna told Yuuko about him being the only one capable to give her the capacity to use the Valis sword's full power in order to defeat Glames, they went to Sutherland and made their way to the Nirvan temple beating all of Nizetti's tests until they reached him. Nizetti warned her about the possibility that this power might not be enough to stop Glames, but Yuuko still wanted to use it anyways against him, Nizetti gave her the Valis armor's ultimate form and she along with her allies went to the Dark world to face Glames. When they learned they were deceived as Glames went to the Human world and made his own tower, Yuuko and her friends went to the tower. Before facing Glames, Nizetti appeared and told them that only Yuuko could face Glames and healed fully her HP and MP before her final battle. His destiny after this remains unknown as he doesn't appear in Valis IV; it's presumed that he could actually be alive in his temple or died from old age at some point from the 15 years between both games.
Nizetti is an intelligent, calm and reflective old man. Even though his predictions are almost always right, sometimes they aren't, like when Yuuko defeated Glames, contrary to what he predicted. He is also helpful when he can (like before the battle with Glames).
Nizetti can summon armor guards in his temple. He can levitate, make illusions and teletransport himself even to other worlds. He can also restore Heal Points and Magic points. He is the only one who can give Yuuko her ultimate Valis armor's form.
Nizetti appears in all versions of Valis III testing Yuuko before giving her the Valis armor's ultimate form. He also appears to fully heal Yuuko before facing Glames.
He also appears in the Mugen Senshi Valis manga by ZOL where his role is a bit changed. He, along with Valna, appears after Yuuko defeated Venon in Tokyo city to help her continue her fight against Rogles.
- Nizetti is possibly the oldest character from the series.
- He is also one of the few male characters that supports the protagonists.
- Nizetti tests Yuuko but is never fought by himself.
- Nizetti's name has an Italian feature.
- Nizetti is featured in the Genesis cover of Valis III.
- Nizetti's seiyuu, Naoki Tatsuta, also voices Asura in the same game.
- Nizetti's role in Valis IV is taken by Yuuko, as she is the one who tests Lena Brande and gives her the Valis sword and the Valis armor.