The shogunate suspects that Western Catholics had been involved in spreading the rebellion and Portuguese traders are driven out of the country.

While there is no evidence that Europeans had directly incited the rebellion, Shimabara Domain had been a Christian han for several decades, and the rebels had adopted many Portuguese motifs and Christian icons.

Consequently, in Tokugawa society the word "Shimabara" solidifies the connection between Christianity and disloyalty, constantly used again and again in Tokugawa propaganda.

The policy of national seclusion is by 1639 made more strict .

An already existing ban on the Christian religion is now enforced stringently, and Christianity in Japan survives only by going underground.

Iemitsu officially closes off Japan from the rest of the world, limiting trade to the Dutch and English merchants ensconced on ...