Mukai's troops eventually arrived in Edo. When Adams saw how seedy Edo Castle looked compared with Osaka Castle, he was disappointed. It was not defended by stone walls, just surrounded by low and long mounds of earth with fortifications atop. The fortifications were also made of earth and covered with bamboo and weeds. Inside these fortifications there was the main castle and a smaller one, both low buildings constructed with hinoki (Japanese cypress – high quality, rot resistant), with their roofs covered with moss and weeds. They looked like the huts of bandits. There was a new small house with white walls and roof tiles, which looked like a sort of castle. If this humble house was Ieyasu's stronghold, Adams doubted Ieyasu would be the future king. When he asked Suminokura Ryōi, whether it was perhaps Ieyasu's second home, Suminokura smiled at Adams and answered ‘it is his stronghold’.

Suminokura then began to explain why Ieyasu's stronghold was so humble. In 1590, governor-general Toyotomi Hideyoshi had given Ieyasu Kantō hasshū [eight districts of the Kantō] in the East of Japan. These districts were Sagami, Musashi, Awa, Kazusa, Shimosa, Hitachi, Kouzuke and Shimotsuke. The first Edo Castle in Musashi district had been built by O￣ ta Dōkan in 1457. Since then, it had been occupied by successive Uesugi Sadamasa and Hōjō Ujitsuna lords. When Ieyasu became the lord of the castle,he was advised by his loyal retainers to build a new castle, but he ignored their advice and instead pioneered a canal between the castle and the Hirakawa estuary in Edo Bay. He wanted the canal to transport weapons from the sea. At the same time, he recovered land from the sea, using the earth excavated during the canal construction. On this land he built three new towns called Zaimokucho, a wood dealers’ town, Funa-cho, a seafaring town and Yokkaichi- cho, a market town. In a move of which the modern-day town planner would approve, a separate residential area for the townspeople was created with views over the man-made lagoons. There was no good water in the reclaimed ground, so Ieyasu set up the waterworks that channelled and purified the water from Inogashira, in the western part of Edo.