It was a sister car of the Lexus HS 250h that was released earlier in July, and the two models shared the basic components although they were differentiated by their interior and exterior designs.

The highly aerodynamic body design extended even to the flat and smooth underfloor covers, attaining a drag coefficient of 0.27 which was among the best in its class.

The name comes from the Japanese word "sai" -which means "talent" and "coloration" when written with the Kanji character.

Reprogramming the hybrid control unit also provided an increase in fuel economy on the test cycle.

On November 15, 2017, the Sai was discontinued and replaced by the Lexus ES 300h, which was released in Japan on October 24, 2018.