We want your blood

A couple of days ago I was sat in one of my first year classes, munching my lunch and minding my own business when a kid ran up to me and shouted something. Unfased (it happens every day) I responded in Japanese, telling him I didn't know what he just said, and asking him to repeat it in english, which I suspected he was unlikely to be able to do. To my surprise the homeroom teacher was in earshot and repeated the line in english:

"What blood type are you?"

For a minute this threw me, and with what was obviously a puzzled look on my face I looked away to find the entire class staring at me. At this point I want to add a fictional narrative that did actually spin through my mind very quickly at that point:

[ To my horror I found the entire class staring at me with wide, vacant eyes, food bowls held with unmoving limbs, saliva dripping steadily from the corners of slack mouths. A low moan seemed to eminate from the entire room as the children slowly rose to their feet and turned towards me... ]

Ok, so that was genuinely what went through my head. I asked the homeroom teacher to repeat the question and he did. Still asking about my blood. I motioned in what I hoped was an indicator to the blood and veins at my wrist, and the teacher nodded. Still puzzled, I told them I had no idea what my blood type was. And, with my response met with a frown, I muttered under my breath "and you can't have any."

It wasn't until later I remembered my Taiko sensei had explained this to me at the end of year enkai a few months before. The Japanese read blood types as we read horoscopes, and each one is supposed to give you a certain (predictable) personality. I then gently cursed myself for not remembering this at the time and giving a suitable comedic response. Next time I'm asked "what is your blood type?", I'm going to say "green."