3. Alternately squeeze the two yukkuris' bodies, circulating the bean paste throughout both.
4. After the bean paste has been well mixed, squeeze it all into one side and cut off the side you don't need. Done.
5. You can eat the mixed yukkuri, or return it to its parents. By mixing their bean paste, you can also produce new types of yukkuri. Have fun trying out the various possibilities.
Can you also translate what they are saying in the first panel (which git skipped), so we have a complete translation (and probably a translation edit).