Clean the squid thoroughly, removing the spine and inedible parts while keeping the body intact.
In a bowl, combine leeks, onion, tomatoes, soy sauce, sugar, garlic, ginger, and calamansi juice.
Stuff each squid about three-fourths full with the mixture.
Reattach tentacles and secure with a skewer.
Score the outside lightly.
Prepare a very hot grill or hot coals.
Grill the squid, basting with the remaining liquid as it cooks.
Turn as needed and cook until lightly charred and just done.
Remove from heat and let rest for 5 minutes.
Slice and serve warm.