|Name: Masato Kusaka|
|Designation: Kamen Rider Kaixa|
|Weapons: Kaxia Shot, Kaixa Blaygun|
|Gear: Kaxia Driver, Kaixa Shot|
|Mecha: Side Basshar|
|The Kaixa Gear was the third set of Kamen Rider Gear developed by the Smart Brain Corporation to protect the Orphnoch King. The Kaixa Gear was more powerful, but slower than the Faiz Gear. It still did not match the Delta Gear for speed or strength, but possessed greater functionality. Mastao is a member of Ryusei School who was apparently absent from the reunion, but signed the autograph card. He is the only Ryuseiji who was capable of wearing the Kaixa Gear without disintegrating afterwards and as such is the Gears primary wearer. He had a great deal more Orphnoch DNA implanted into him, but whose neck was snapped by Yuji Kiba as Kaixa when Kusaka's Orphnoch DNA started to run out, with Kiba using it towards the end of the series. As children, Mari often saved him from bullies and as a result he has fallen in love with her and is willing to go to elaborate lengths to eliminate any obstacles between him and her. He passionately despise the Orphnochs, regardless of whether they "have souls" or not and swears to destroy them all. His hatred was driven by the events that took place at the Ryusei School reunion and he continually wipes his hands to remove the imagined blood he remembers from that night. Masato Kusaka is the only one to have worn all three of the Kamen Rider belts (Faiz, Kaixa and Delta). He wore the Faiz Gear to trick Yuji Kiba. He wore the Delta Gear to battle the Beetle Orphnochs (Rhinoceros and Stag).
The Kaixa Gear is a collection of seemingly normal items developed by the Smart Brain corporation based the Kaixa Mission Memory. A small metallic card key with the Kaixa symbol on it, the Mission Memory can be inserted into certain Kaixa Gear, turning the item into a powerful weapon. The Gear is usually stored inside a Smart Brain secured briefcase until needed. More notable is that the Kaixa Gear requires a much greater deal of Orphnoch DNA than the other gears and as such is of greater risk to use. The Kaixa Gear set was in fact incomplete when it was first obtained and used, missing the Kaixa Pointer Binoculars until they were found by Masato. At the end of the series, the Orphnoch King destroyed the Kaixa Gear while Kiba was using it, which started his slow destruction.