According to Tomonobu Imamichi, Heidegger's concept of Dasein in Sein und Zeit was inspired – although Heidegger remained silent on this – by Okakura Kakuzō's concept of das-in-der-Welt-sein (being-in-the-worldness) expressed in The Book of Tea (PDF) to describe Zhuangzi's philosophy, which Imamichi's professor Ito Kichinosuke had offered to Heidegger in 1919, after having followed private lessons with him the year before:
‘Ito Kichinosuke, one of my teachers at university, studied in Germany in 1918 immediately after the First World War and hired Heidegger as a private tutor. Before moving back to Japan at the end of his studies, Professor Ito handed Heidegger a copy of Das Buch vom Tee, the German translation of Okakura Kakuzo’s The Book of Tea, as a token of his appreciation. That was in 1919. Sein und Zeit (Being and Time) was published in 1927 and made Heidegger famous. Mr. Ito was surprised and indignant that Heidegger used Zhuangzi’s concept without giving him credit. Years later in 1945, Professor Ito reminisced with me and, speaking in his Shonai dialect, said, ‘Heidegger did a lot for me, but I should’ve laid into him for stealing’. There are other indications that Heidegger was inspired by Eastern writings, but let’s leave this topic here. I have heard many stories of this kind from Professor Ito and checked their veracity. I recounted this story at a reception held after a series of lectures I gave in 1968 at the University of Heidelberg at the invitation of Hans-Georg Gadamer. Japanese exchange students attended these lectures, and I explained that there were many other elements of classical Eastern thought in Heidegger’s philosophy and gave some examples. I must have said too much and may even have said that Heidegger was a plagiarist (Plagiator). Gadamer was Heidegger’s favorite student, and we ended up not speaking to each other for 4 or 5 years because he was so angry with me’ (Imamichi 2004, pp. 123–124).[3][4]
Martin Heidegger Interview with a Monk (English Subtitles)