If you're looking for anime similar to Thunder Mask, you might like these titles.
In present day Tokyo, traveling has never been more comfortable than aboard the Lightning L808, Japan's new luxury passenger plane. One day, on what seemed to be a routine flight, Haruka Leina and the plane's passengers were unaware of the mysterious and top secret cargo brought aboard, which attracted the attention of international terrorists set on obtaining it. Now, with a dangerous hostage situation at hand, only special agent Laika Strange and brave Leina may be able to save the passengers, and keep the deadly cargo from falling into the wrong hands...
The story of the anime revolves around two youths. Hikaru has been enjoying his normal school days in middle school and Alma is a Mecha-Ude Wielder who can be activated when he is attached to human beings. There are exciting adventures and battles following the two of them in the story.
Masaru is 5th Grade boy who loves Crush Gear very much. But he does not have his own original Gear. One day he and his family move to a new town where Masaru meets a hero called “Crush Kid.” “Crush Kid” is a well-known Gear Fighter who uses a gear called “Garuda Phoenix.” Masaru accidentally participates in the Gear fight using “Garuda Phoenix” and wins the game. This was the beginning of his life as a Gear Fighter.