和暦の日付を取得するファンクション＋エイリアス。

Get-JapaneseDate.ps1

<#
.SYNOPSIS 
    和暦の日付を取得します。   
.EXAMPLE 
    Get-JapaneseDate
.EXAMPLE 
    Get-JapaneseDate -format "ggyy年MM月dd日"
.EXAMPLE
    Get-Date -Year 2015 -Month 12 -Day 31 | Get-JapaneseDate
#>
Function Get-JapaneseDate(){
    [OutputType('PSCustomObject')]
    [cmdletbinding()]
    param(
        [Parameter(Mandatory=$false, ValueFromPipeline=$true, Position=0)]
        [datetime]$date = (Get-Date),
        [Parameter(Mandatory=$false)]
        [string]$format
    )
    $Culture = New-Object Globalization.CultureInfo("ja-JP");
    $JPCalendar = New-Object Globalization.JapaneseCalendar;
    $Culture.DateTimeFormat.Calendar = $JPCalendar;

    # Formatチェック
    If($format -ne ""){
        return $date.ToString($format, $Culture);
    }
    
    # 独自のCustomObjectを返す
    Write-Verbose $date.ToString("ggyy年M月d日 (dddd) HH:mm:ss", $Culture);
    return [PSCustomObject]@{
        Era      = $JPCalendar.GetEra($date)
        EraName  = $date.ToString("gg", $Culture)
        Year     = $JPCalendar.GetYear($date)
        Month    = $date.Month
        Day      = $date.Day
        Date     = $date.Date
        RawValue = $date
    }
}

New-Alias jpdate Get-JapaneseDate