Inspiration - Buddhist Kongōrikishi

Buddhist, Kongōrikishi or Niō, are pairs of wooden or clay figures that flank the doorways to Buddhist temples.  Carved to be guardian spirits (Vajrapani) to Buddha, the figures are also meant to serve as meditations on power and courage. 

Kongōrikishi:  Agyō (left) and Ungyō (right), colored wood from the Kamakura Period in 1288 AD, National Treasure House, Nara, Japan
​(Photo source)

The tradition might have its roots in Greco-Buddhism. Ancient sculptural examples exist of the Greek hero Herakles serving as an early protector of Buddha. 

 Kongōrikishi:  Agyō (left) and Ungyō (right), sculpted by Kaikei and Unkei in colored wood during the Kamakura Period in in 1203 AD, Nandaimon, Nara, Japan (Photo source)

  "He vibrates with energy and spiritual power which you can absorb from him in times of need."
- Zen monk, Suzuki Shōsan (1579-1655) in regards to meditating on the figures. He even urged his students to adopt the fearsome expressions of the sculptures. 

Kongōrikishi:  Agyō (left) and Ungyō (right), clay from the Wadō Period in 711 AD, Hōryuji Temple, Nara, Japan (Photo source)