The real estate developer behind the towers that have reshaped central Tokyo’s skyline isn’t done yet.

Azabudai Hills, a ¥580 billion ($4 billion) complex of offices, shops, restaurants and luxury residences — including a hotel and an international school — opened its doors last month to join Roppongi Hills, Toranomon Hills and other developments by Mori Building.

Yet Shingo Tsuji, the closely held company’s CEO, was already talking about his next mega "Hills” project and potentially backing an integrated casino resort in the metropolis of 14 million when he sat down for a recent interview.