The Great East Japan Earthquake 2011 occurred on March 11 (Meguro, 2011). Group homes (GH)-A and B, run by a private company, were located in the coastal area of Kesen-numa city and damaged by the disaster. Fourteen of the 17 elderly residents living prior to the disaster in GH-A and B were evacuated to another GH-C run by the same company. The number of residents prior to the disaster in GH-C was nine, but almost tripled to 23 after the disaster, and several residents started to live together in one room. Compatibility of residents living in the same room was examined. Worsening of behavioral abnormalities caused by overcrowding was anticipated, but surprisingly behavior was improved (see Supplementary Table S1, available as supplementary material attached to the electronic version of this paper at www.journals.cambridge.org/jid_IPG).