The Byakko Inves, originally Yuya Sumii, is an advanced Inves and an antagonist in the first episode of Kamen Rider Gaim.
The Byakko Inves was created when Yuya Sumii ate a premature Lockseed he found in Helheim Forest. Ingesting the fruit caused him to mutate into an Inves which later became the Byakko Inves.
As his friends Kouta Kazuraba and Mai Takatsukasa were searching for him in Helheim Forest, the Byakko Inves attacked them. Using the Orange Lockseed and Sengoku Driver given to him, Kouta transforms into Kamen Rider Gaim and defeats the Byakko Inves, unknowingly killing his friend.