According to wiki: grooming is the action or behavior used to establish an emotional connection with a vulnerable person who is typically, but not always, under the age of consent and sometimes with the victim's family, to lower their inhibitions with the objective of sexual abuse.
By this definition, the dom's goal isnt to establish an emotional connection with the sub but to break down his barriers, by practicing dom-sub play. The sub is very defensive towards doms in general and his health seems to be affected by his unresolved sub urges. Thus the dom uses small commands like kneel, sit, present etc, to get him used to commands or at least he did this in the beginning...
Hello translator here :) I already replied to someone else's question about their dynamic, so I'm just gonna copy-paste what I said before in here.
The reason Yutaka is able to have Play with Kazunari specifically is because Kazunari is the only Dom he truly trusts. Yutaka himself doesn’t fully understand why he has such severe trust issues with other Doms or why Kazunari is the exception (yet). That’s connected to their past and will be explored much more later . Hope this helps!

Is this grooming.