sentences:  However, the policy of national seclusion introduced by the Tokugawa bakufu in the Edo period effectively ended the influence of western art on Japanese painting, with the exception of the use of perspective, which was discovered by Japanese artists in sketches found in European medical and scientific texts imported from the Dutch via Nagasaki.In 1855, the Tokugawa "bakufu" established the "Bansho Shirabesho," a translation and research institute for western studies, including a section to investigate western art.This section was headed by Kawakami Togai, whose assistant Takahashi Yuichi was a student of English artist Charles Wirgman.