Beat yolks of the Egg (4), Caster Sugar (45 gram), and Salt (1/4 teaspoon) over a water bath until the sugar and salt have completely dissolved, and the egg yolks are creamy.
Mix Black Sesame Paste (53 gram) with Water (43 gram) and add them to the egg yolk mixture.
Preheat oven to 425 degrees F (220 degrees C).
Beat egg whites with a mixer on low speed until they become white and frothy.
Gradually add Caster Sugar (45 gram) in intervals, allowing the sugar to dissolve before each addition. Just before stiff peaks start to form, add the Lemon Juice (1 1/2 teaspoon). Stop beating when stiff peaks have formed.
Add 1/3 of the meringue to the egg yolk mixture and mix well.
Sift in the Cake Flour (72 gram) and Baking Powder (1 1/2 teaspoon) and mix to combine.
Fold in the rest of the meringue.
Transfer to a chiffon cake mould and run a pair of chopsticks through the batter. Knock against the table to allow air bubbles to escape. Pour some batter into a small baking pan as the extra cake for the ears.
Bake for 20 to 25 minutes. The extra cake only needs to bake for around 10 to 15 minutes.
Beat Heavy Cream (50 gram) and Caster Sugar (4 gram) until soft peaks form.
Transfer the cream to a piping bag and pipe on Totoro's belly and eyes.
Place Chocolate Buttons (2) for the pupils. Use Chocolate (to taste) to pipe on his nose, whiskers, and details on its stomach.
Cut out the ears from the extra cake. Make small incisions on the side of the cake for its ears. Pipe in some chocolate as 'glue' and attach the ears.