It's not "Taiyaki", it's "Tuna roast"! -"Book tuna" and "Chutoro" from Tsukiji "Sanokiya" with plenty of red bean paste
Tsukiji "Sanokiya" sells "tuna roast" instead of "taiyaki". You can choose from two items, the "bluefin tuna" that "the outer skin is crispy and the contents are Ogura bean paste" and the "middle toro" that "the contents are anko and apricots".