  There is a long history of an effort made to explore musical elements with
the entities and spaces around us, such as musique concr\`ete and ambient
music. In the context of computer music and digital art, interactive
experiences that concentrate on the surrounding objects and physical spaces
have also been designed. In recent years, with the development and
popularization of devices, an increasing number of works have been designed in
Extended Reality to create such musical experiences. In this paper, we describe
MR4MR, a sound installation work that allows users to experience melodies
produced from interactions with their surrounding space in the context of Mixed
Reality (MR). Using HoloLens, an MR head-mounted display, users can bump
virtual objects that emit sound against real objects in their surroundings.
Then, by continuously creating a melody following the sound made by the object
and re-generating randomly and gradually changing melody using music generation
machine learning models, users can feel their ambient melody "reincarnating".
