Divide red bean paste into six equal portions and roll into balls. Each should be 25-30g each or about the size of a ping pong ball. Put in refrigerator while you assemble the mochi dough.
In a microwave safe bowl, mix shiratamako, sugar, and water. Cover and microwave for 2 minutes, or until mochi dough is cooked through.
While still hot, turn out mochi onto a surface dusted with katakuriko. Divide into six equal parts. Roll each part into a flat circle, roughly 3-4" in diameter.
Take one circle, keeping the rest of the mochi covered with a damp towel to keep it from drying out. Place a red bean paste ball in the center, and wrap the mochi around it, pinching the edges to seal into a ball. Roll daifuku in more katakuriko to keep it from sticking.
Repeat with the other five mochi circles and red bean paste balls.
With kitchen scissors, snip the top of each daifuku. Press a cored strawberry into the opening of each daifuku, and you're done! Daifuku need to be eaten the day they are made.