OUT OF CHARACTER
Backtagging: Of course! I am all for backtagging.
Threadjacking/threadhopping: Also fine by me unless it's a private or sensitive conversation
Fourthwalling: Please don't. It would explode Ishimaru's brain.

IC - LOVE
Hugging: Hugs are great. Ishimaru may be confused and surprised and flustered, but go for it!
Flirting: Of course. But he may not notice. Oops.
Kissing and so on: Well, I can't imagine this coming up for quite a while!

IC - WAR
Fighting: Absolutely, though Ishimaru will try to avoid physical conflict.
Injuries: Definitely, but let's talk it out first please.
Killing: Talk to me!

IC - OTHER
Telepathy/mind-reading/psychicness: General present and "surface" thoughts are fine. Anything else, please ask first.
Language Barrier: Ishimaru speaks Japanese, but as a top student in his class, he will also be a master of student-level English. Apologies in advance.