Lupin had twin sons, around 15 years old, and lived with them out in the country somewhere. One of his sons looked like him and wanted to become a rancher, so he was all into rodeos and cowboys and such. His other son was a Jigen clone, as he wanted to be him.
Lupin and rancher son were returning from some sort of fair and Lupin decided to race his son back home. The two were running and Lupin turns to see his son laying on the road, having been hit by a car. He is very sad by this.
Jigen clone son is sitting and messing with his gun when he looks up and runs off. He gets to the scene of the accident and runs up to his dead brother. He kneels down and sobs. For some reason he tosses his gun away. He looks down and sees his brothers gun, a cork gun that looked like an old time revolver. He grabs it and stares off.
Jigen clone then becomes his brother, cutting his hair and shaving and wearing clothes his brother would wear. He has decided to be a rancher, to fulfill his brothers dreams.