According to wiki
On October 8, 1895, Empress Myeongseong (Queen Min), the wife of Emperor Gwangmu (King Gojong) of Korean Empire was assassinated by a group of Japanese assassins (the Eulmi Incident). In February 1886, Kim assassinated Josuke Tsuchida (土田譲亮) for being involved in the murder of the queen in Chihapo, Hwanghae Province.
Who was Tsuchida?
the resulting "Report from acting administrator Hagihara Moriichi of Incheon Consulate on the current situation of Incheon" (在仁川領事館事務代理萩原守一ヨリ仁川港ノ情況ニ付続報ノ件, April 24, 1896) describes Tsuchida as a "commoner from Nagasaki Prefecture" (p. 6, "長崎縣平民土田譲亮") and an "employee of a Nagasaki trader on a business trip"(p. 7, "貿易商大久保機一の雇人").
But wiki continues
this does not prove that Tsuchida was not involved in the assassination of the Empress Myeongseong, as the assassination was done by not only Japanese soldiers but also many Japanese Ronins as described in the report by Isizuka Ezo (石塚英藏), the Japanese consultant to the Korean Empire at the time, which is recorded in a book published by a Japanese historian Kentaro Yamabe (山邊健太郞).  In addition, Kim stated in his biography 'Baekbeom Ilji' (白凡逸志) that Tsuchida was carrying a sword and had identification papers that showed him to be a Japanese army lieutenant
(1)Min was assassinated by several Japanese
(2)Tsuchida was Japanese
(3)Kim thought Tsuchia was a Japanese lieutenant.
It does not follow Tsuchida was a Japanese who was involved in assassination of Min.
After all witout further evidence, it is reasonable to suppose, based on the Japanese report that Kim killed an innocent Japanese who had nothing to do with the assassination of Min.
This illogical writing is the reason why the Korea -related articles of wiki are vandalized by Korean nationalists.
I am not sure whether Kim should be called a terrorist or an assassin.
But he was a murderer who killed an innocent person.
And Korean people worship the murderer because he killed a Japanese whom he mistakenly considered to be involved in the assassination of Min.
Moreover Korean media*1 reports that when a Korean blogger writes Kim ku was the terrorist on the blog, the blog had nearly 100,000 access from Korean netizen, mainly complaining that the blogger is sick. The article reports that the provider Naver can not shut up the blog, can not reveal the blogger's real name because of the freedom of the thought----This is the intellectual level of Korea media----they pick up moron's skirmish on the Internet, insinuating that the site should be shut down because it is against Korean nationalism.
Marmot wisely writes
This is evidence of why it may be better to study Korean Studies outside of Korea than within — there’s still quite a few “no-go” areas
Chosun ilbo (1)(japanese)(2)