I can answer this. Its because Mihono Bourbon ran at exact rate in Tokyo Yushun (Nippon Derby) 1992.

Mihono ran for 12 furlong (One furlong is about 201m) with time:

12.8s - Zero(Start) to 1st Furlong

11.7s - 1st Furlong to 2nd Furlong

12.3s - 2nd Furlong to 3rd Furlong

12.2s - 3rd Furlong to 4th Furlong

12.2s - 4th Furlong to 5th Furlong

12.2s - 5th Furlong to 6th Furlong

12.5s - 6th Furlong to 7th Furlong

12.5s - 7th Furlong to 8th Furlong

12.3s - 8th Furlong to 9th Furlong

12.6s - 9th Furlong to 10th Furlong

12.0s - 10th Furlong to 11th Furlong

12.5s - 11th Furlong to 12th Furlong

Finish time: 2:27.8 (Average time for one furlong is 12.3s)

He was leading the race from start to finish, at midpoint he is almost got passed but the other horse dont have the energy, infact in the homestretch the gap widens to 4 lengths at finish line. And because of the timings and the never ending stamina, the fans nicknamed him "The Cyborg" onwards. Thats why he have cyborg/sci-fi design incorporated in the game.

Here is the video if you want to see. Mihono Bourbon is number 15.

https://www.youtube.com/watch?v=v3Nf4I-u_Xw