I've ordered the following item from Yahoo! Auctions Japan:

https://page.auctions.yahoo.co.jp/jp/auction/o1089527027

55 当時物 NEC PCエンジン コアグラフィックスI... - ヤフオク!

【ストアのため落札後はヤフー新システム「取引ナビ」でのお取引です。】 商品詳細 ★同梱お取り置きは最初の落札日から3日間です。★ 一部の心無い方のために申し訳ありませんが 新規の方、評価の悪い方は入札の削除をさせて頂きます。 当時物、中古です。付属品や状態は写真のものがすべてです。 コントローラーは2個あります。おまけにボンバーマンのソフトが付属します。ケース等はございません。 経年相応です。外観は特に大きく目立った問題はなく概ね良さそうです。画像の通りです。 本体にONランプがない仕様なので実設置しない

It's basically a complete PC Engine console which should include all the necessary cables and controllers to set it up. It includes one HuCARD game, and I've separately ordered a pile of additional HuCARD games just in case this one doesn't happen to work.

In the item description, the seller basically says that they can't guarantee that actually turns on or otherwise functions due to the lack of a power LED anywhere on the console, so it's considered a "junk" (untested) item.

I've just received it in the mail, and I'll unpack it and set it up tonight. This market will resolve YES at the close time if I am able to turn on the console and play a game on it without any additional work. If I am unable to get any game to play on it, the market will resolve NO. Even if it has some simple problem that I am able to find and repair, this will still resolve NO if I have to actually disassemble the console to do so.

I'll leave the market open for 24 hours and report the results afterwards. I will not be betting in this market myself.