kvasir:
I don't follow your comment, posetcay. If you just capture the ko then you will either live with o1 after white takes back or by connecting if they don' take back. There are enough liberties so you won't have to worry about ko.

kvasir:
Taking the ko first looks like a valid solution to me. If black didn't have a much needed liberty then taking the ko appears to lead to a direct ko.

Morph:
After F19-G19-H19-J18, can't White tenuki? It's already alive with double ko.

timqzm:
ko

navy:
After G19,E19,F19,F18 and C19, doesn't E18 make a dead shape?

qzyki:
G19, E19, F19, F18, C19 works without a ko, but it is marked as wrong.