Kai
Kai is a T-Fanger in Telefang and is Shigeki's rival. His goal is to cut down antenna trees so that it is impossible to travel through them. Unfortunately for Shigeki, this hinders his task to defeat Sanaeba.
Kai's Denjuu depends on what version it is. In Power Version, his Denjuu is Angios, and in Speed Version, it is Gymnos. Oddly enough, in Power Version, his Denjuu has a type advantage over Shigeki's main Denjuu (Angios is Sky-type, Crypto is Forest-type), but in Speed Version, it is exactly the opposite: his Denjuu has a type disadvantage over Shigeki's (Gymnos is Mountain-type, Fungus is Grassland-type).
He first appears at the Antenna Tree in Palm Sea. He has one Denjuu: In Power Version, he has an Angios at Level 20, and in Speed Version, he has a Gymnos at Level 20.
His next appearance is right at the entrance of Cactos Ruins. This time, he has his main Denjuu at Level 60, and a Raygirth at Level 56.
He also appears after fighting Golaking and automatically losing to him. When Shigeki finds him, he asks to get Kai's main Denjuu's phone number. Kai is very stubborn and walks away, but Shigeki gets the number anyway. When fighting Golaking again, this Denjuu automatically has a type advantage against him, despite being the wrong type.
Kai can be found a fourth time in Palm Sea after completing the game. Shigeki must warp to the cave with the switch that activates the Antenna Tree in Palm Sea and then warp back on the island to find him. He does not battle, however.
Kai has three different, interchangeable names in the bootleg: Boundary, Ken, and Kate.
In the manga
Kai appears in the Telefang 1 manga, acting much as he does in the games. Rather than having one partner Denjuu, he seems to command a flock of Angios.