Neither of the 'twins' seems to notice Accelerator's presence, as they had no real reason to. Akito is much too busy making Agito try on clothes more his style, since there are barely a handful of outfits Akito owns that Agito would wear himself. And Agito, for his part, is too busy indulging Akito's every whim because his other half has been altogether much too... Depressed. Sad. Stressed. On edge. There isn't much Agito can do to help right now other than help distract Akito with other things.

So, yeah. He's stuck shopping with his other half.

But it isn't something he can really complain about, since in all honesty he enjoys it. It's nice for them to be able to fuss over each other physically. Hold hands. Hug. Offer physical comfort. Yes, it makes it harder to protect Akito, but at the same time it makes it easier to keep him safe in other ways.