epicardium

Japanese: epicardium

…the heart is surrounded by two inner and outer connective tissue layers, the pericardium. The inner pericardium is a thin layer that covers the outer surface of the heart. It turns over at the base of the great blood vessels that enter and leave the heart, transitioning to the outer pericardium and becoming the sturdy pericardium (Herzbeutel). Part of the pericardium is attached to the diaphragm and fixed in place. …

From "Pericystitis"

…Pericarditis is a general term for inflammatory lesions caused by various factors in the pericardium (consisting of the epicardium, which covers the surface of the heart, and the pericardium in the narrow sense, which covers the heart, separating it from the narrow pericardial cavity). Pericarditis is usually broadly divided into three types: acute pericarditis, chronic pericarditis, and congenital pericarditis. …

*Some of the terminology explanations that mention "epicardium" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…心臓は内外2葉の結合組織性の心膜pericardiumに包まれる。内側の心膜は心臓の外表面をおおう薄い心外膜epicardiumであり，これは心臓に出入りする大血管の根部に至って反転し，外側の心膜に移行し，じょうぶな心囊Herzbeutelとなる。心囊の一部は横隔膜に癒着し固定される。…