Since April, lower milk production has triggered a shortage of butter.
バター(batā) = "butter"
お一人様一点限りの制限をつけさせていただきます(o-hitori-sama itten kagiri no seigen wo tsukesasete itadakimasu) = "we limit purchases to one per customer"
逼迫(himpaku) = "tight [supplies, finances]"
Update from May 18 LA Times:
Butter spread thin in Japan
By Bruce Wallace, Los Angeles Times Staff Writer
Bread is buttered on neither side as the milk product has become hard to find. There are reasons, but try telling that to the bakeries.