This OVA for the second season is a single normal episode. Most of the time in this episode is taken up by Hachiman going on a 'date' with Iroha and near the end when Yukino and Yui see a picture he goes on a short date with them too. That's the entire OVA. There's no drama and it's really chill compared to the second season. The characters are the ones described in the paragraph above. The animation, voice acting and music are the same as or similar to the second season. It doesn't really add anything to the story aside from maybe shedding a bitmore light on Iroha and doesn't seem like it's required to understand the story. It is however a nice break from the awkwardness/drama so I'd recommend watching it because of that.