It's Keizo Kuroda, it looks like!
This was Ayu's old hair and make up guy. He left at some point after (miss)understood into Startin' / Born To Be... so they're on good terms still! Woo! (It was rumored that he left due to personal issues with Ayu but it seems to me that he just left because he'd been with Ayu for a long time and was moving on.)
His blog entries about seeing the concert and attending the afterparty:
http://ameblo.jp/kurodakeizo/entry-10601332285.html
http://ameblo.jp/kurodakeizo/entry-10600572517.html
http://ameblo.jp/kurodakeizo/entry-10600763258.html