Kamen Rider Build: Grimm Eclipse

『𝑲𝒂𝒎𝒆𝒏 𝑹𝒊𝒅𝒆𝒓 𝑩𝒖𝒊𝒍𝒅: 𝑮𝒓𝒊𝒎𝒎 𝑬𝒄𝒍𝒊𝒑𝒔𝒆』 (仮面ライダービルド: グリムエクリプス) is a Japanese tokusatsu drama in the Kamen Rider Series, created by Ishimori Productions and Toei Company. It is the first series to air for a full period in the Xenon era run, and the first spin-off Kamen Rider Series in said era. It is also the first Kamen Rider series to be fully animated, and the first cross-over series, Build crossing over with the American animation, RWBY, created by Rooster Teeth. The series started on January 5, 2019, joining Soshi Sentai Elemenranger in the Super Hero Time line-up. After Build's conclusion, Elemenranger would be joined by a currently-unknown series for the Super Hero Time block.

The tagline for this spin-off is ""Experiment: commence." (実験: 始めます.) The main motif of this season, alongside science and scientific principles, is the concept of a 'best match'.

Plot
Once upon a time, three different realities existed; the prime world as well all knew it, one where an elusive tower known as the Skywall split the world into three, and one where the moon split into two, where the world plunged into a war between humanity and a mysterious race known as the Grimm.

On one fateful day, history is re-written, and the latter two worlds are merged together into one unknown world, and many years later, an individual is thrown into it, in all its chaos. But does he have the answer to the elusive 'best match'?

Beacon Academy

 * Team RWBY
 * Ruby Rose
 * Weiss Schnee
 * Blake Belladonna
 * Yang Xiao Long


 * Team JNPR
 * Jaune Arc
 * Nora Valkyrie
 * Pyrrha Nikos
 * Lie Ren