Initially, Japanese observers thought the Taiping Rebellion was a nationalist revolt by Ming China loyalists. This perception was encouraged by for instance the rebel slogan "Destroy Manchuria, Revive Han China
(滅満興漢)". Thus, Japan believed the rebellion to be an attempt by the subjugated Han Chinese natives to free themselves form their Manchurian overlords.
The original information is that Taiping Heavenly Kingdom was a Ming restoration movement by the descendants of the Ming ruling house, or perhaps a movement by the Heaven and Earth Society. They conquered Nanking in 1853 and threatened Peiking. This information reached Japan from 1852 onward.
- Eto, J.
katsu kaishu zenshu [Complete Works of Kaishu Katsu]. Tokyo: Keiso Shobo (1970).
Japan was traditionally friendly towards the Ming dynasty. During the Manchurian conquest, many in the Tokugawa Shogunate wanted to dispatch an army of 40,000 strong to assist the beleaguered Ming defenders (in response to the request of Nicholas Iquan Gaspard, in the name of the Longwu Emperor). This was forestalled by the rapid collapse of Chinese defences and defection of Nicholas Iquan, but Japan continued to provide limited material support to the Ming remnant in Taiwan.
Consequently, the belief that the Taiping rebels were fighting to end the Manchurian occupation created favourable first impressions in Japan. Several works of fiction were produced around this time, for example the New Tales of Yunnan
(雲南新話), depicting the restoration of Ming China in a war of liberation clearly inspired by the Taiping rebellion.
As more news reached Japan however, it became apparent that the Taiping Rebellion was primarily a religious conflict. Coupled with the widespread destruction and bloodshed the rebels were inflicting, Japanese opinions soured. For example, the Samurai Hibino Teruhiro, who was part of a delegation to Shanghai in 1862, writes that:
《日比野輝寛・贅肬録》 長毛賊以復明大義起兵 無可非議 惟以邪教惑滋愚民 釀成大亂 災及十省 難以遏禁
《Zeiyuuruku》 The Long Haired bandits launched their rebellion in the name of restoring Ming. That's not something we can criticise. However, by using cults to brainwash peasants, they caused a massive chaos. Ten provinces were afflicted by the disaster.