@terriblyuncute that is the thing that gives me the most hope, because the bond that he has with Koito is genuinely true while with Tsurumi he is just being manipulated (and he is well aware of that too).
However, as we saw from that last panel Tsukishima has now renewed faith in Tsurumi and went back to the same man we saw in the first chapters, killing on his orders without any hesitation.
I'm a bit sad to see this develpment on him, to be honest (since I like him), but I understand that, after Usami died, Tsurumi is lacking true followers around him so somebody has to have his back and it falls on Tsukishima - just like Tsurumi planned from the very beginning mind you.
At this point I don't see any redemption for his character and I'm just hoping my boy Koito will make out of this mess alive.