“Have a Ball with Pencil Puzzles—Slitherlink for expert6”
This book contains over 90 Slitherlink puzzles for experts.

“Have a Ball with Pencil Puzzles – Kakuro for expert 6”
This book contains over 90 Kakuro puzzles for experts.

“Just Right! Sudoku (a bit hard) 6”
This book contains 105 Sudoku puzzles, most of which are of medium difficulty.

“Puzzle Communication Nikoli Vol.194”
Nikoli is the most advanced pencil puzzle magazine in Japan. The first issue was published in August, 1980.

“Nikoli Puzzle Book Reprint Edition Sudoku 2”
The puzzles in this volume are all the puzzles of “Pencil Puzzle Book Sudoku Vol.23”. This volume contains 100 puzzles.

“Japanese Fill-in Puzzles by Nikoli”
This book contains over 50 fill-in (In Japanese:”skeleton”) puzzles using a variety of Japanese words.

“Tappuri Suiri Puzzle (Logic Puzzle)”
This book contains over 50 logic puzzles. The contents of this book are in Japanese, so be prepared.

“Puzzle x Riddle: Challenge from the Riddlers’ Club”
“Puzzle x Riddle: Challenge from the Riddlers’ Club” contains over 40 puzzles that need a spark of inspiration and logical thinking. Knowledge of Japanese is necessary to solve puzzles in this book.

“Sudoku for Absolute Beginners”
This book contains very basic explanations of Sudoku, along with over 30 beginner-friendly Sudoku puzzles.

“Masterpiece selection of “Slitherlink for the very best” Vol.1”
This book contains over 100 challenging Slitherlink puzzles carefully selected from previous editions.