Prepare vinegared rice as per Uramaki post. While rice is cooking, prepare the tofu pouches.
In a medium sized pot, bring about half pot of water to boil. Add tofu pouches and boil for 1 to 2 minutes. This is to remove excess oil. Remove tofu pouches and allow them to cool.
Squeeze out excess water, and cut off a small section, about ¼ of one side of each tofu pouch. Gently pull open at the slit to make pouches.
Pour away the water used to boil tofu pouches. Bring 1½ cups (360ml) water to boil. Add dashi, soy sauce, sugar, and sake. Return tofu pouches back to pot. Simmer for 15 minutes. Remove and drain tofu pouches.
Mix vinegared rice with sesame seeds in a wet bowl or tub. Wet hands, take a generous amount of rice and shape into a rectangular block. Open one tofu pouch and insert the block of rice.
Neatly tug or fold in the edges of the tofu pouch.
To serve, place rice side down on a dish.
Notes
If you are using seasoned tofu pockets (ajitsuke inari kantofu), skip all the tofu preparation steps.