Modi's Japan visit: Why is it important?

Indian Prime Minister Narendra Modi is visitng Japan from August 21. He has extended his sojourn in the eastern most oriental nation by a day.

This is being seen as a significant pointer – a pointer that India sees Japan as its best ally in Asia and that both want to tame China, which is hell bent on turning South China Sea into ‘Lake Beijing’ in Japanese PM Shinzo Abe’s words
What is the significance of Modi’s third foreign tour – after Bhutan and Nepal? Here is a lowdown:
* By extending his tour of Japan by one day, Modi is signaling a new relationship with Japan. He intends to send a signal to China that its aggressive designs in South China Sea will be met equally aggressively. Japan has boundary dispute with China and has been fighting to preserve regional security balance. Adding India, which too has to counter China’s String of Pearls around India and the encirclement along the Himalayas, will put China in a spot.
* India and Japan will sign a defence agreement. This is significant because this is the first time that Japan will be signing a defence cooperation agreement outside its traditional allies like US, UK, Russia and Australia.
* Japan has always been pressing for a Democratic Security Diamond for Asia. It includes closer cooperation between US, Australia, India and Japan to deal with Chinese plan to destroy strategic balance in the Indo-Pacific region. The navies of US, India and Japan had participated in an exercise last month.
* India will gain from this because it is facing increased Chinese incursions into Ladakh region and China is firmly entrenched in Pakistan-occupied Gilgit Baltistan, which was part of Jammu and Kashmir till 1948. China is already building roads close to Indian border in Tibetan region. Japan’s cooperation will help check Chinese designs.