/// <summary>
        /// 地球時間をエオルゼア時間に変換する
        /// </summary>
        /// <param name="localTime">
        /// 地球の現地時間</param>
        /// <returns>
        /// エオルゼア時間</returns>
        public static EorzeaTime ToEorzeaTime(
            DateTimeOffset localTime)
        {
            // UTCにおける差分を算出する
            var diff = localTime.ToUniversalTime() - EorzeaTimeOriginByUTC;

            var totalSec = diff.TotalSeconds;

            var delta = totalSec * LTETRatio;

            var secound = (int)Math.Truncate(delta % 60d);

            delta -= secound;
            delta /= 60.0d;

            var minute = (int)Math.Truncate(delta % 60d);

            delta -= minute;
            delta /= 60.0d;

            var hour = (int)Math.Truncate(delta % 24d);

            delta -= hour;
            delta /= 24.0d;

            var day = (int)Math.Truncate(delta % 32d);

            delta -= day;
            delta /= 32.0d;

            var month = (int)Math.Truncate(delta % 12d);

            delta -= month;
            delta /= 12.0d;

            var year = (int)Math.Truncate(delta);

            // 年月日は1オリジンなので1を加える
            var et = new EorzeaTime();

            et.Year   = (1 + year) % 10000;
            et.Month  = 1 + month;
            et.Day    = 1 + day;
            et.Hour   = hour;
            et.Minute = minute;
            et.Second = 0;

            return(et);
        }
        public static DateTimeOffset FromEorzeaTime(
            EorzeaTime eorzeaTime)
        {
            var delta = 0d;

            delta += (eorzeaTime.Year - 1) * 12 * 32 * 24 * 60 * 60;
            delta += (eorzeaTime.Month - 1) * 32 * 24 * 60 * 60;
            delta += (eorzeaTime.Day - 1) * 24 * 60 * 60;
            delta += eorzeaTime.Hour * 60 * 60;
            delta += eorzeaTime.Minute * 60;
            delta += eorzeaTime.Second;

            var totalSec = delta / LTETRatio;

            var utc = EorzeaTimeOriginByUTC.AddSeconds(totalSec);

            return(utc.ToLocalTime());
        }