$submit = mb_convert_encoding($submit,'SJIS');
switch($submit){
case mb_convert_encoding("べっかんこ",'SJIS');
$filename = "http://h.ula.cc/dance/?P=$page&kenken=$keyword";
break;
case mb_convert_encoding("讃岐る",'SJIS');
$filename = "http://s.s2ch.net/search/-/?STR=$keyword&COUNT=10&P=$page";
break;
case mb_convert_encoding("どーも",'SJIS');
$filename = "http://www.domo2.net/search/i/s.cgi?w=$keyword&p=$page";
break;
default;
$filename = "http://niwango.jp/mobile/new_search/search_niwango.php?K=-&q=$keyword&hiro=x&s=$page";
break;
}

なんでかこれで動いた( ﾟ∀ﾟ)y─┛~~