Counter strategies:
1) overwhelm your attacker with pleasantries idol style. lead with "Oh are you a fan, It's so nice to meet you, what's your name? Oh is that spelt with kanji A or kanji B? Where are you from? Do you live locally? So how long have you been a fan? oh really why thank you." pull out notebook remark how difficult it is to get accurate viewer profiles, tell them you're running late for lunch so you'll have to leave them for now but emphasise how much you appreciate the support and how you're looking forward to interacting with fans in the future, then walk away calmly while they're still confused, report them as a stalker.
2) damsel in distress: scream as loud as possible try to avoid him catching hold of your mouth people should come running or open their windows, either they'll run to escape the crowd or be captured.
3) fight back and run: hard kick the knee out or groin break the wrist grab fend off other attempts to grab as he's bent down slam your bag into his face run as fast as you can back to the nearest group of people pepper spray if you have it easily available.
4) hired muscle: bodyguard splats the assailant.