In the anime the character of Gren is a dude that was forced to take an experimental drug while he was in prison, and the drug caused him to grow breasts. The whole reason why he was in prison and why he had to take the drug was tied into his character arc, and he was most definitely still a guy, he just happened to have tits. When they swapped it over to the live action version they cast a nonbinary actor to play the part and effectively made the character trans, because this is apparently something that was "wrong" in the anime. Yet another reason to stay the hell away from the live action version.