HI,
I tried 

NatashaOtomoskiIsSatoshiNakamoto
SatoshiNakamotoIsNatashaOtomoski

No luck.
I think we should convert each letter to its ascii and then create key directly from that .
so NatashaOtomoskiIsSatoshiNakamoto  becomes   5JQoiBW5eKd6gFvakcX2mJmCmKgJJsbRvDbVzcfeUaYqJGzDUXn
(as suggested in various previous post )
I don't think we need Brainwallet.

I think that there are a few important clues:
- the '.txt'  at the end is a clue I think but I don't know to what?? (I treid to save a file with that name but got : 'A file name can't contain any of the following characters: \ / : * ? < > |')
- The anagram NatashaOtomoski  suggests to me that the name SatoshiNakamoto  should be in the answer.
- the 21 which seems to point to the max number of bitcoins. Or what else
- then there is the strange 'COMB'. I see no connection to Bitcoin there.  (unless you comb the knots out of  'NatashaOtomoski' to get 'SatoshiNakamoto')   ToGetOutSatoshiNakamotoInTheEnd
- and the curious start transaction to fill up https://www.blockchain.com/btc/address/179sxfh6rw6bHSo5wVUhLP96k46QaEzVP. Should we check out the orig. adresses further ?
  (if you look at the adresses.. you see quite a history of small tranactions.)

And it could also be that there is no solution (trolling ?? ).

Intriguing