Reddit mentions of Impro for Storytellers

Look to the right of your screen and down a little bit.

Based on your recent post, I feel like you're looking for a training program in book form. The UCB Manual is the most comprehensive and closest thing to that, but take it all with a grain of salt as at a certain point it does start teaching the UCB style. Novices may take some things to mean these are this-is-the-only-way-to-do-things hard and fast rules, but it's just the way to play their aesthetic. Be open to other possibilities.

Some books, like the recent Will Hines book or Napier's Improvise, are very good but I recommend them after you've done a bit of improv. Same with this, this, and this.

Johnstone's Impro is great for a peek into story-based
British style improv. His passages on status are invaluable.

I personally don't care for Huack's Long-Form Improv, mostly because at the beginning of the book he tries to distill all improv comedy down into an equation, which is way too simplified for my tastes. Improv Wins is a decent, breezy book, but I don't like how they pose scenario questions and then suggest that there is a "correct" response you should make. Still, if you can glean insight from a book, even an understanding of disagreement, then that makes the book valuable in some way.

The only real way to learn improv is to do it and not be afraid to make mistakes and missteps along the way. You will not get improv right the first time.

Impro: Improvisation and the Theatre by Keith Johnstone

Impro for Storytellers by Keith Johnstone

Not on a very regular schedule, but yes. I'm happy to hear that -- now you simply must read Johnstone's books! :-)

Impro: Improvisation and the Theatre is his first book, and more "theoretical", I would say (that is, using improvisational theatre as a vehicle for expressing ideas that apply in many other contexts). It discusses (to repeat my other post) teaching, human interaction, creativity/spontaneity, storytelling, self-perception, among other things; it demonstrated (directly, to me) things about my own (creative) thought process, which is always fun.

Impro for Storytellers is his other book, which is more "practical" (that is, several chapters that are lists of exercises with discussion) and more focused on theatre, which is why I didn't name it initially. Even so, it's a great book to read even without ever performing directly, just to understand oneself and the process involved.

In a way improvisation has a lot to do with Taoism (as I understand them), and I appreciate them for similar reasons, like constant doublethink/unthink, living in real-time, and acceptance of the irrational/imagination (which is a surprisingly difficult thing).

(After you read these books, by the way, your opinion on them would always be appreciated. :-) )