Japanese Geodetic Datum 2000 (vertical) height - EPSG:6694

WKT

VERTCS["JGD2000_vertical_height", 
	VDATUM["Japanese_Geodetic_Datum_2000_vertical"], 
	PARAMETER["Vertical_Shift", 0.0], 
	PARAMETER["Direction", 1.0], 
	UNIT["Meter", 1.0]]

WKT2

VERTCRS["JGD2000_vertical_height", 
	VDATUM["Japanese_Geodetic_Datum_2000_vertical"], 
	CS[vertical, 1], 
	AXIS["Gravity-related height (H)", up, 
		LENGTHUNIT["Meter", 1.0]], 
	ID["EPSG", "6694"]]

Data from @esri/proj-codes

{
  "wkid": 6694,
  "latestWkid": 6694,
  "macro": "PE_VCS_JGD_2000_HT",
  "name": "JGD2000_vertical_height",
  "wkt": "VERTCS[\"JGD2000_vertical_height\",VDATUM[\"Japanese_Geodetic_Datum_2000_vertical\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "VERTCRS[\"JGD2000_vertical_height\",VDATUM[\"Japanese_Geodetic_Datum_2000_vertical\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",up,LENGTHUNIT[\"Meter\",1.0]],ID[\"EPSG\",\"6694\"]]",
  "description": "Japanese Geodetic Datum 2000 (vertical) height",
  "authority": "EPSG",
  "version": "8.4(10.3.1)",
  "deprecated": "no",
  "areaname": "Japan - onshore mainland",
  "extent": {
    "slat": 30.94,
    "nlat": 45.54,
    "llon": 129.3,
    "rlon": 145.87
  }
}