In 1965, this model kit company began their slot-racing line by producing 1/24 scale kits of a Lotus-Ford type 29 copied straight from the Strombecker model, and a BRM P261 F1 that was a clone of the Cox model. The kits used a brass chassis with a drop arm and were designed to fit the Mabuchi FT16 motor, that as in most Japanese slot car kits, was not supplied. They were packaged inside vacuum formed trays inside cardboard boxes with vigorous color illustrations. The chassis actually improved over the basic Revell frames, but the quality of the bodies was very basic. Doyusha, visibly inspired by Strombecker, also produced a Mercedes W196 and a Vanwall F1 kit using the same mechanical components, sold in similar packaging. At the same time, two 1/32 scale kits were offered in similar boxes and using similar gear, that of a Jaguar KX120 and a Ferrari Testa Rossa. In 1966, Doyusha re-issued the previous kits, now with vacuum plated bodies in silver, gold or red. They also produced four new 1/24 scale kits in more elaborate packaging. A Scarab-Buick and a Porsche 904 were direct and obvious copies of the 1965 Monogram models from the USA but their chassis were also obvious copies of the Tamiya models, themselves inspired by Monogram. A Ford GT and an Aston-Martin DB5 were somewhat more original and completed the line, the last of the 1/24 scale models produced by Doyusha. A 1/17 scale Go Kart inspired by the smaller Strombecker model was their last slot car racing product.
Doyusha typifies the product of the Japanese toy industry in the day, virtual copies of toys spied in US or European trade shows, that they were able to replicate quickly then market them to the original product customers and undercutting their prices.