3D model: Otoshi-ari-hozo-shikuchi by thejoinery on Sketchfab
Assembly insights
Hozo Tsugi represents the cornerstone of Japanese frame joinery. The tenon (hozo) fits precisely into the mortise (ana), creating a strong mechanical connection. Mastery of this joint teaches layout accuracy, chisel control, and the importance of a tight fit. Nearly every frame structure—from doorways to temple columns—relies on some form of hozo work.
Historical context
Hozo Tsugi is the most widely used joint in Japanese carpentry. Variations range from simple stub tenons in furniture to through-tenons in shrine framing. The proportional relationship between tenon length, width, and mortise depth has been refined over centuries. Related forms include Kama Hozo (sickle tenon), San Mai Hozo (three-piece mitred dovetail), and Tsuki Uchi Wa (blind mortise).
Construction steps
- Lay out the mortise position on the receiving member using a marking gauge and square.
- Chisel the mortise, working from both faces if it passes through; keep walls square.
- Mark and cut the tenon on the mating piece to match mortise dimensions.
- Saw the tenon cheeks and shoulders; pare to the line with chisels for a snug fit.
- Test-fit dry; the joint should require light tapping and seat fully without gaps.
Where to see this joint in Japan
- Ise Grand Shrine — Mie — post-and-beam framing throughout
- Traditional door and window frames — Machiya townhouses — Kyoto and Kanazawa
Variations
Through-tenons expose end grain on the back face; blind tenons (Tsuki Uchi Wa) hide the connection. Wedged tenons lock permanently; drawbored tenons pull joints tight. Kama Hozo and San Mai Hozo extend the basic concept to corners and three-way intersections.
Applications
- Door frames
- Window frames
- Table legs
- Cabinet construction
Tools required
- Dozuki saw
- Nomi chisels
- Marking knife
- Square