Wouldn't Yoshikumi need light in order to manipulate shadows? I mean, shadows are cast by light shining on something and then obscuring that light from a certain area. The absence of light - darkness - isn't a"shadow", since it's not created by the obscuration of light, but rather the absence of it.

... Unless you're going with: At night, the sun is on the OTHER side of the earth, s the earth casts a shadow over its own, other half, nyaaaa~! 8D

Or wyut Iunno, sleep, nao, need it! FLARGH!