@Lightbrand Depends on the ultimate goal behind the seal. I haven't read ahead, but I'm assuming that he was sealed because he was an evil demon king at war with humans. If he was turned into a horrifying monster, he'd just be attacked constantly, and he'd grow to hate humans.
However, this way, he would have to at least learn compassion and kindness to get be loved (since very few like animals that are rude or violent). There's also a decent chance that he would care about whoever breaks the seal, considering the requirement. So, even if he killed her, that would just cause himself pain, and he'd be less likely to cause that same pain towards others, and less likely to desire war.
However, this way, he would have to at least learn compassion and kindness to get be loved (since very few like animals that are rude or violent). There's also a decent chance that he would care about whoever breaks the seal, considering the requirement. So, even if he killed her, that would just cause himself pain, and he'd be less likely to cause that same pain towards others, and less likely to desire war.