I will be briefly explaining what this OVA is about, so I have put a spoiler warning in advance.

Love Live! Nijigasaki Gakuen School Idol Doukoukai: Next Sky is about Isla, a character we have seen previously in season 2, travelling to Japan to learn more about being a school idol. We see her learn what it means to be one, and she even ends up performing with them before going back to London. Before she does, the girls help her realise that she can become an idol if she wants to, with the help of others (such as Penelope, for her).

The OVA felt so special and expanded our view on school idols. Now there are canonically school idols in London lol (I heard it was mentioned before but idk). I haven't finished Nijigaku Season 2, so I hadn't seen Isla nor Penelope previously, but they were so adorable! Especially Isla. She seemed very enthusiastic and honest when it came to becoming a school idol. I hope to see more of the two in the future.

The music, as usual, was great, the storyline was amazing, the characters were cute and it was just perfect overall. I watched this not knowing what to expect, and finished it satisfied. It was very entertaining and had me wanting more by the end. Apparently this is being released on Blu-ray this August, let's hope it gets released not only in Japan but in the UK as well for Love Live fans like me! (and other places, of course. We should all be able to enjoy it together!)

So, overall, I would give this OVA a 10/10. Possibly one of the best OVAs i've watched. I definitely prefer it to Love Live's other OVA, the one in the first anime (although, that one is good, too. Watch it if you haven't!).