noun
abrupt plot twist; unexpected story development
Colloquial term, often used in anime/manga/game fandom to describe a sudden, extreme, or nonsensical turn in the story that feels like it came out of nowhere.
最終回でいきなり宇宙人が出てきて超展開すぎる。
In the final episode, aliens suddenly appeared—what an abrupt plot twist.
あのアニメは毎回超展開で、先が読めない。
That anime has an unexpected story development every episode; you can't predict what will happen next.
Compound of 超 (chō, 'super, ultra') and 展開 (tenkai, 'development, unfolding'). The prefix 超 intensifies the sense of an extreme or excessive plot development.