It is a comment describing the anime that I saw:
"WHILE TAKING RESTRAINING OUR PRISONER MORGAN, HE MANAGED TO SLICE AND KILL GARP-SAN!"
Is this "taking restraining" a valid usage?
Whether it's a "valid" usage is up for debate, I suppose, but it looks to me like the translators omitted a conjunction:
While taking and restraining our prisoner Morgan, he managed to slice and kill Garp-San.
In other words, while Morgan was being taken and restrained – or perhaps we could say, while Morgan was being arrested – Garp-San was killed by a sword.
Using two verbs with a conjunction such as and is quite common in English. For example:
In fact, nothing limits us to just two verbs; we could use three or more:
Include signs that remind everyone to wash hands before eating, drinking, or preparing food.
This really looks like a missing word, and I'd strongly advise against doing this without a conjunction:
Mr White hurt his neck while restraining controlling the prisoner.
There is certainly a completely grammatically correct form of two gerunds adjacent in a sentence:
He sighed starting cleaning the floor.
We had such fun opening nesting dolls!
Spreading growing branches wider and wider the oak reigned over the forest.
Yes, it is possible to amend those examples to add an article or a pronoun between the gerunds, but it's not required.