Quote Originally Posted by Kraco
As if he's actively holding back a lot and is not honestly calm and composed as his basic nature.
Well, that's a given. He doesn't like Chisaki looking after other guys. Since Tsumugu is taking a rather passive role while letting Chisaki get over things on her own, I believe he actually values their time together. Anyone who intrudes that pisses him off more or less.

Tsumugu is '1st in line' for Chisaki while she's deciding over Hikari... and Tsumugu doesn't like queue jumpers.

Private-time-invasion aside (and the threat that being under the same roof brings along), I think Tsumugu would also be nicer to Hikari (besides his obvious threat status) because:

a) Hikari doesn't like Chisaki
b) Chisaki likes Hikari.

I don't believe that Tsumugu is conscious of all of this though, but that should be what's going on.

edit: forgot to say, that CGI was rather obtrusive. Obtrusive CGI = bad CGI.