Free rigs from applybot Japan for Maya:

Intermediate student download
https://www.applibot.co.jp/recruit/3dadopt/3drig/dl/ab_rig_B.zip

Beginner Student download
https://www.applibot.co.jp/recruit/3dadopt/3drig/dl/ab_rig_A.zip

Source: https://www.applibot.co.jp/recruit/3dadopt/3drig/