When registering a domain, you are indicating by yourself the contact of the person or company that will be used in the domain. NIC.UA does not register domains on itself or another company, neither on an individual or a fictitious person that is acting in the interests of the company.
It is up to you to choose who will become the owner of the domain. Nevertheless, NIC.UA strongly recommends that you do not specify fictitious characters or nicknames as the domain owner.
If you lose access to the domain, the only way to prove that you are the owner is to provide documents. If the owner says "Gingerbread Man" or "Captain America" it will be difficult to solve this case.