Hawk Envelope – Hiroshi Kumasaka. Made from a square sheet of paper. Loose flap must be glued down to seal. Adapted from a fold attributed to Hiroshi Kumasaka (from whose initials its name is taken), OKK vol. 4, ’80, Nippon Origami Association magazine (Japanese Origami Society) vol. 2, Japanese publication. Heart shape can be formed on tip of flap thus producing a Valentine envelope. Compare Kumasaka version.