To make the sauce for the ginger chicken, combine the soy sauce, sake, sugar and grated ginger in a small bowl and stir together until the sugar has dissolved.
Heat a frying pan over medium heat along with a splash of oil, and add the chicken in a single layer. Fry until it's browned on one side (about 2-3 minutes)
Flip the chicken over and continue cooking until for another minute.
Use a paper towel to soak up any excess oil in the pan.
Add the sauce and caramelize it around the chicken until there's almost no liquid left. Let the chicken cool before packing it into a bento.
To assemble the bento, add your rice to your bento box first. This provides a base to arrange all your other ingredients.
Arrange the chicken next to the rice.
Add some frill lettuce to separate the chicken from the vegetables, and if you have a deeper bento box, you may want to pad the bottom of the box with some lettuce too.
Add the slices of tamagoyaki using the broccoli to fill the spaces around them.
Fill the remaining space with the strawberry and slice it in half if necessary.
Decorate the bento with the flower-shaped carrots.