sunken hearth; sunken fireplace
back (side); reverse; other side; inside; background; dark side (e.g. of society)
front and back; inside and outside; two sides; duplicity; double-dealing; being two-faced
secretly; covertly; tacitly
behind closed doors; behind-the-scenes; (under the veil of) secrecy
Imperial Palace; Imperial Court
one's mind; the bottom of one's heart; inner feelings
(with a) successful outcome; (ending in) success
arena (e.g. international arena)