Well, Makoto didn't notice because the effect of the medication Illum was receiving weren't that strong to cause issues.Hmm, Ilum meeting Makoto when he is out of drug seems only added in manga, or LN too?
?.?...
but this meeting moment just feels like the story try to "blame" Makoto for not noticing Ilum state/condition when Makoto actually meet Ilum face to face, I just dont like this added part n feels it a bit unnecessasy...
@.@...
Plus it seems that Illum had figured out that the medication was having a negative affect on him, since he noticed how his emotions were getting uncontrollable when near Makoto.
And considering what he saw, its possible that Illum might have tried to avoid doing anything to Makoto or anyone related to him in the future.
But because Makoto ended up erasing Illum's memories of the past few hours.
Not only Illum forgot about the negative effects of the medication he noticed, but also what Makoto is like.
Thus allowing him to fall more into the trap of stronger medication.