Yuki's activites

I dont really understand how I can add tags, that are not already used for that manga. Like I type in that small box my tag I want to add and click enter and save but the tag wont be added. I dont get itttt, pls can someone tell me what I do wrong?

Now I'm curious, will he actually have a actzally regret and be sorry for his actions? I mean that poor boy had a whole in his stomach TWO times, and what not in his body- I want to see Ian cry on his knees and beg for forgiveness at the very least