On 24 May (Fri.), Dr. Yosuke Mizuno (Frankfurt U.) visited iTHEMS and gave a 15min talk at iTHEMS coffee meeting. Dr. Yosuke Mizuno is a core member of the Event Horizon Telescope (EHT) project to observe “Black Hole Shadow”. He is a core author of the paper V (theory part) of the first detection of the black hole shadow of M87, which was press-released in the world on 10 April, 2019. In the 15 min talk, Dr. Yosuke Mizuno explained why the black hole shadow is expected from Einstein’s Theory for General Relativity. He also introduced the angular resolution of EHT, which was expected to be smaller than angular size of the black hole shadow of M87. After great efforts of the EHT collaboration, finally the EHT collaboration succeeded to take images of the black hole shadow of M87. This was a big discovery, which confirmed the existence of a Black Hole (independently from gravitational waves), mass of the black hole of M87 (about 6 billion solar mass), and the theory of general relativity. For future works, he introduced some unsolved problems such as confirmation of rotation of the black hole of M87, mechanism of jet formation of M87, and possible correction of Einstein’s theory of general relativity. After the talk, “endless” Q&A was followed between Dr. Yosuke Mizuno many iTHEMS members.