Hi there! Thank you for your querie about the Humanistic teachings of Nichiren Buddhism. Let me start by saying that the title "Humanistic Buddhism" is rather sematically weak: because there are no 2 types of Buddhism: one Humanistic and another non-Humanistic. I think we should alter the title into "Buddhist Humanism". If you trace the word Humanism you'll find various views: Christian Humanism, secular Humanism...etc... and adding the term "Buddhist Humanism" is appropriate. 

 Secondly, the term Humanistic Buddhism or Buddhist Humanism, whether in China or Japan or the USA, is based on the Buddha's teachings - in particular the teachings of the Lotus Sutra. (The article mentions this clearly). The Lotus Sutra - of course - is not a private property of a certain temple or nation (Chinese, Japanese etc...) Buddhism of the Lotus Sutra is a universal teaching for all Humanity.

Historically, it was TienTai of China who placed the Lotus Sutra as the highest of the Buddha's teachings. Later it was introduced to Japan and the Tendai Sect emerged upholding the Lotus teachings, which was the ground for Nichiren, who appeared in 1222, to declare his teachings based solely on the Lotus Sutra. Currently, a 12 millions Samgha Nichiren Buddhist group (the Soka Gakkai International) is actively working for: "Spreading Buddhist Humanism in the Community" http://www.sgi.org/about-us/members-stories/spreading-buddhist-humanism-in-the-community.html

 Nichiren Buddhism focuses on the Lotus Sutra: “Buddhist humanism:  It is a philosophical perspective that reflects the core spirit of the Lotus Sutra”
Buddhist Humanism: http://www.daisakuikeda.org/main/philos/buddhist/buddh-05.html

 I think it is more accurate and more professional to refer to Buddhism as either Theravada or Mahayana. In China or Japan, you have Buddhist schools which are either Theravada or Mahayana. There is no such thing as "Chinese" Buddhism and "Japanese" Buddhism. Using the term Chinese or Japanese Buddhism is plainly wrong. For example Zen has branches and temples in both Japan & China. It remains Zen. No need here for confusing "passport" added to Buddhism. Nichiren Buddhism is found all over the world but mostly parcticed in Japan, this does not make it Japanese, but correctly: a Mahayana school based on the Lotus Sutra. It is even not logical to speak about Humanism and Humanity and in the same time restrict Buddhism to artificial national descriptions of  Chinese and Japanese terms. 

 Wikipedia articles must be impartial and must bring various views. Humanistic values of Buddhism cannot be patented to this temple or that priest only. All respect worthy people working to spread Buddhist Humanism must be acknowledged. I am doing research to include the participation of various Mahayana schools in the teachings of Humanism of the Buddha teachings which are for all Humanity. Thank you for your input and let's cooperate to improve the article.