そのころ。。。 = Sono koro... = Back then...
The Barry Manilow songs being referenced seem to be "I write the songs" and "Mandy".
The disclaimer at the bottom references the opening credits of Monty Python and the Holy Grail.

Piro speaks:
If you don't know which barry... that's a good thing.
Lame, stupid, silly, totally off the cuff, this comic, and that is Dom's real reaction to this strip when i showed it to him :P