Generally the show is truly a "spin-off" of the first season. Light hearted and focused more towards Miyuki's thoughts and her group of friends.
This is an underrated anime. You MUST watch the first season first or at least read the Yuutousei manga before watching as it is not a standalone anime. It is not part of the main timeline series.
Spinoff Definition: a spin-off (or spinoff) is a radio program, television program, film, video game or any narrative work, derived from already existing works that focus on more details and different aspects from the original work (e.g. particular topics, characters or events)