Hmm...I don't know if I'm going to get bashed for this, but I don't think Yuuji really knows that Shana likes him a lot. He does know, however, that Kazumi feels that way, and what Ike said might have influenced his actions of chasing after Kazumi first a little.
Besides, we don't know exactly how he feels about either Shana or Kazumi...yet. For all we know, he might be chasing after her as a concerned friend instead, although that still doesn't seem to take the label of spinlessness off him, it seems...
