Relative date format in Japanese

/*
 * Return relative date format in Japanese, eg: 5時前
 * max param indicates when to return absolute datetime
 * Default is 30 days
 */
function ja_relative_time($stamp, $max = 2592000) {
    $interval = date_create('now')->diff(new DateTime($stamp));
    if ($interval->s >= $max) {
        return $stamp;
    }
    $suffix = ( $interval->invert ? '前' : '' );
    if ( $v = $interval->y >= 1) return $interval->y . '年'. $suffix;
    if ( $v = $interval->m >= 1) return $interval->m . '月'. $suffix;
    if ( $v = $interval->d >= 1) return $interval->d . '日'. $suffix;
    if ( $v = $interval->h >= 1) return $interval->h . '時'. $suffix;
    if ( $v = $interval->i >= 1) return $interval->i . '分'. $suffix;
    return $interval->s . '秒'. $suffix;
}