New Delhi, July 2 -- NEW DELHI - When Japan's Prime Minister Sanae Takaichi landed in New Delhi on Wednesday for her first official visit to India, she carried more than diplomatic routine - she brought a structural commitment. By Thursday afternoon, India and Japan had signed 16 formal agreements spanning artificial intelligence, clean energy, maritime security, and defense technology, setting the terms for what both governments called a "new chapter" in the relationship between Asia's second- and fifth-largest economies.

The 16th India-Japan Annual Summit formalized ties that have been building through years of cautious summitry. Prime Minister Narendra Modi welcomed Takaichi at Hyderabad House in New Delhi, where the two agreed a join...