Tetsuwan Birdy Decode: The Cipher
To be honest, I'm a little surprised. In the sense that the ova is actually irrelevant. Yes, it is the transition between seasons 1 and 2 and shows the aftermath and current situation of the protagonist's girlfriend from season 1.
"Possibly" this would have played a role later, but since this is irrelevant to season 2 and probably would have only been picked up again in season 3, there is no need to watch it.
It's just an everyday life episode, even if the average quality of this ova episode, exceeds the individual anime episodes.
Honestly, I would have been more interested in the relationship of the two characters, but this is probably or not possible.
This is actually the 13th episode of the first season. It's both counted as separate, and as a part of the first season because it's more of a bridge between seasons one and two.
As such, I reviewed this with the rest of the first season.
However, to say a little more about this episode, and it being a bridge between the season... It really doesn't have that much to do with the second season, I think. Very misleading, as it's mostly about Nakasugi and Senkawa, and the second season doesn't focus on their relationship very much.
Though, I actually enjoyed this episode more than I enjoyed the rest of the show. Not that there weren't parts of the show that I didn't enjoy as much, but this episode as a whole... I liked it.