Kogaryu has been making takoyaki for many decades now - the extra spring onions and yuzu sauce make them special. http://www.kougaryu.jp/index.html
Go at the crack of dawn (like a bit before 5.30am) any day for the tuna auction, get a bowl of tuna sashimi at a stall, and then go take a nap at the hamarikyu botanical gardens nearby.
It's absolutely vital you get the burnt miso ramen. Whether you're a "Ramen? That stuff from a packet?" person or an "I wait for 2 hours at NYC's Ippudo" snob (like me), you'll freak out it's so good.
