Place 10 strawberries into a medium bowl and use a fork to mash. Add mochi, sugar and water. Cover with plastic wrap and microwave for 2 minutes at 500 watts. Give it a quick mix and microwave again for 2 minutes at 500 watts. Mix until it comes together to make mochi.
In a separate bowl, add cream cheese, strawberry jam and powdered milk. Stir to combine.
Fill a tray with potato starch. Pour out mochi onto the tray. Use hands to cover mochi with the potato starch, then smooth out to flatten.
Divide mochi into four sections. Top each piece of mochi with about 1 tablespoon each of anko and strawberry milk cream mixture. Wrap into a ball and transfer to a plate seam side down. Repeat with remaining mochi.
With kitchen shears, make a slit on top. Place one fresh strawberry in each slit before serving.