what do you mean filler episode during a filler? if you're talkin about the "pendulum arc" no it's not a filler. the pendulum arc is really included in the original story line and came in the exact part where it did in the manga. though, the filler they did in ep. 213 is nothing but shitload of crap and has degraded the series a lot, as i was really anticipating to watch the battles after the "pendulum arc".
君の腕の中 あたたかいよ 僕は言えるかな
It's warm in your arms; I wonder if I can say it
弱さを 今 翼に変えて
I'll change weakness into wings now
"Good bye, yesterday"