Pericardium

Japanese: pericardium

The heart is surrounded by two lobes, an inner and outer pericardium, which is made of connective tissue. The inner pericardium is a thin epicardium that covers the outer surface of the heart. It turns over at the base of the large blood vessels that enter and exit the heart, transitioning to the outer pericardium and becoming the sturdy pericardium (Herzbeutel).

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 "pericardium" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…心基部には心房や心臓に出入りする大血管(大動脈，肺動脈，肺静脈，上下の大静脈)があり，周囲臓器と連なる。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。…