hmmmm I'ma not so sure.....meh don't think that's right but hmmm....maybe I'ma wrong?? :/
anyway,speaking of colds,well I think it's pretty hard not to get cold when u outside all day & all night on rain or snow,don't 'chu agree?? honestly,I think Ikuto doesn't have the best immune system but still not sure we can call it "weak".....I would rather say....Idk....medium?? 'cos if u pay attenton,in anime,also manga,Ikuto wasn't all that sick,right?? ONCE he get cold,when he was outside on snow not dressed 4 winter,ne?? but there was NO OTHER TIME when he was ill,he was just having headache & didn't feel so well 'cos of violin,actually X egg & all...but back then,he wasn't sick :P sooo...guess medium we should say,da??