|This article is about a/an rider in Kamen Rider Decade.|
Arata (アラタ Arata) is an agent of ZECT under Otogiri who uses the Gatack Zecter to transform into Kamen Rider Gatack. Arata first thought Tsukasa Kadoya as just a simple ZECTrooper whose been slacking off during a raid on a group of Worms his group found. Until Kabuto's arrival during a raid, Arata noticed that Tsukasa and his crew not from his world, explain to them about the world they are in, such as ZECT organization and Worms' ability to mimic other appearances. He is the only member of Otogiri's group to support Kabuto, and attempts to defend him. But when he sees Otogiri with Mayu, he attempts to reason with him before he is attacked by ZECTroopers, escaping them to call Tsukasa and the others for help as he learns that he and ZECT are being played by Otogiri.
- ―Transformation announcement[src]
- Height: 190cm
- Weight: 134kg
- Punching Power: 8t
- Kicking Power: 9t
- Maximum Jump Height: 19m
- Maximum Running Speed: 100m/8.9s
Masked Form (マスクドフォーム Masukudo Fōmu) is a heavily armored form resembling a pupa. This is Gatack's default form, armed with the Gatack Vulcan (ガタックバルカン Gatakku Barukan) to mow down any Worm unfortunate to stray in Gatack's line of fight in a hail of bullets specialized to kill Worms, until he opens up the horns on the Gatack Zecter, like a switch, to initiate the Cast Off (キャストオフ Kyasuto Ofu) command.
- "Cast Off: Change Stag Beetle!"
- ―Transformation announcement[src]
- Rider Height: 194cm
- Rider Weight: 97kg
- Punching Power: 3t
- Kicking Power: 7t
- Maximum Jump Height: 36m
- Maximum Running Speed: 100m/5.8s
- Finisher Power: 19t
Rider Form (ライダーフォーム Raidā Fōmu) is the sleeker, faster, and more offensive form that resembles the stag beetle motif. In this form Gatack has access to the Clock Up (クロックアップ Kurokku Appu) command which allows Gatack to travel at near-light speeds to match the speeds of the Worms. By pressing a button three times on the belt in succession, Gatack can perform his tachyon-powered Rider Kick (ライダーキック Raidā Kikku), a jumping roundhouse kick. Gatack also has a Rider Cutting (ライダーカッティング Raidā Kattingu) attack, where he takes the Gatack Double Calibur and uses them to perform a scissor-like cutting attack.
- Main article: Gatack Zecter
- Device Type: Gatack Buckle ('Henshin' Belt)
- Animal: Stag Beetle
- Color: Blue
- Cast Off System: Pulling the mandible-like Zecter Horns outward.
- Cast Off Announcement: "CHANGE STAG BEETLE!!!"
- Clock Up System: Slap the Switch-pads on the hip of the belt
- Primary Finisher: RIDER KICK - Gatack presses the full throttle button on the Gatack Zecter thrice and resets its mandible-like Zecter Horns back to their default position. When the Zecter Horns are switched open again, the tachyon energy stored within the Gatack Zecter is released to the Gatack Horns for refinement then redirected down to Gatack's right leg. Once charged up, Gatack sails at the enemy Worm with jumping tornado kick. In the final episode, Gatack channels the tachyon energy to his left leg instead and delivers a traditional flying kick
- Secondary Finisher: RIDER CUTTING - Gatack's alternative attack via the Double Caliburs' scissor configuration that clutches the adversary between the ion-charged blades where they are split in two.
- Rider Belt: A belt designed by ZECT specifically for the Gatack Zecter. Its properties are similar to the Kabuto Buckle, also containing the ability to repair itself. It has also been shown that the energy radiation released from the buckle is capable of reviving a near-dead person.
- Gatack Double Calibur: Gatack's weapons; shotel-like weapons which resemble mandibles, present in Rider Form. They are attached on each shoulder when not in use. He has a golden Plus Calibur on his right shoulder and a silver Minus Calibur on his left. When the Caliburs are interlocked, they create a scissor-like weapon resembling a stag beetle's mandibles; the "RIDER CUTTING" finisher is then activated as the charge on the Double Calibur starts immediately.
- Gatack Vulcan: Gatack's weapons; two shoulder-mounted rotary cannons, one on each side, present in Masked Form. Each vulcan has unlimited ammunition. The vulcan has a shooting radius extended as far as 1 kilometer. A few shots from the vulcans are able to kill multiple Worms in Episodes 23, 24 and 32. Despite the name, they are not actually vulcan guns.
- Arata's last name hasn't been revealed by Toei.