Trim the stems off the shiso leaves and cut them into thirds lengthwise.

Make a slit in the mentaiko and extract the contents.

Cut the spring roll wrappers into thirds.

Place mentaiko, shredded cheese, and hanpen in a plastic bag and knead until smooth to create the filling.

Place one piece of shiso leaf on a spring roll wrapper, pipe 1/12 of the filling onto it, fold diagonally three times, and seal with the flour-water mixture. Repeat to make 12 rolls.