We found 3 Reddit comments about Secret Tokyo ('Secret' guides). Here are the top ones, ranked by their Reddit score.
You're looking for Secret Tokyo by /u/pmustiere.
I picked up this book. The author posts here sometimes as well.
For something a bit different than the standard guides, might I chime in and suggest a guide about Tokyo with a twist (that I actually took a few years to write... kind of self-promotion I know, though I guess it's relevant for this post...)