I think that difference in art with the usual manga by Boichi can be explained by the following sentence on p3 of chapter1
When it's just yumin and I, everything in the world looks cute to me.
We are seeing the date between Kitano Ken and Yumin directly from Ken's point of view, hence the cutish art.
Even thought we don't see Yumin and Ken dating that much in SKR, I think it's only because that's not the theme of that manga. However these date does happens as Ken doesn't have that much "work" anyways. I think "I want to feed Yumin" is made ot show these date that can't fit and doesn't help the plot in SKR.
Edited by Weaper, 05 February 2012 - 03:41 AM.