Greatful Dead (2013)

Nami (Kumi Takiuchi) is a young woman with numerous hangups sprouting from a dysfunctional childhood. She inherits a small fortune that allows her to pursue various interests, many of which are highly abnormal. For example, Nami loves to spy on people who, not unlike herself, have gone crazy from loneliness. She calls these people "solitarians." Perhaps due to a father fixation, her favorite spying targets are old men with stiff boners. One fateful day, Nami spies on an elderly gentleman (Takashi Sasano) watching porn DVDs at home. She soon transitions from a peeping tom into a full-fledged stalker.