Asakura was a member of the Zeon military's Research and Development department, and was the one responsible for developing the deadly G3 nerve gas that they would use to murder the population of Side 2.
Asakura supervised the gassing of Side 2, which was carried out by Cima Garahau and her marines. To get them to carry out the genocide, Asakura lied and told Cima and her marines that the gas would only knock out the population of Side 2 so they could be peacefully moved.
Late into the war, following the devastating losses Zeon suffered at both Odessa and Solomon, Supreme Commander Gihren Zabi ordered the construction of the Solar Ray, a weapon of mass destruction made by carving out an existing colony and converting its shell into a massive laser cannon.
To save resources, Gihren chose to have an existing colony used as the base for the superweapon. Under Gihren's orders, Asakura evacuated the population of the Mahil colony so it could be converted into a colony laser. However, he failed to keep proper records of where the population of the colony was sent to, leading to the relatives of those who lived in the colony losing contact with their families.
Though Asakura successfully completed the Solar Ray, Gihren would never actually use it on the Earth Federation Forces in battle, instead using it to obliterate both his father and General Revil's fleets when they went to go negotiate for peace.
As Zeon's defeat became imminent at the end of the One Year War, Cima Garahau pursued Asakura and attempted to kill him as revenge for him tricking her and her marines into committing a genocide. However, Asakura managed to escape and later avoided punishment at the end of the One Year War by blaming the gassing of Side 2 entirely on Cima and her Zeon marines, forcing them to go into hiding.
Principality of Zeon