This might be a reason for the quick selling of the new Transformers items - a 20th Anniversary sale that started yesterday (June 1st) until June 30th.

In addition to sale items to be featured during this month, purchases during June will earn store credits of varying amounts, and shipments sent during June will have something free thrown in (not necessarily related to the items you had bought though).

Anniversary Sale 2017 Conditions:
• All of our special 20th Anniversary sale items that are ordered within the campaign period of 12:00pm Thursday noon, Jun. 1, to 5:00pm Friday afternoon, Jun. 30, 2017 (all Japan Standard Time, UTC + 9; check your time zones HERE) are eligible for a great bonus: HLJ bonus store credit toward your next payable transaction!
• The amount of bonus store credit varies per sale item. You'll be shown the potential amount of bonus store credit on the final page of the checkout. Your actual bonus store credit will be awarded when the sale item ships.
• Your bonus store credit will appear in the Store Credit section of your HLJ account within 24 hours after your order ships. (Store credit will automatically apply to your next paid transaction or transactions. It is not possible to select particular orders or items that are not the next paid transaction; store credit automatically applies to the next paid transaction, as long as you have store credit.)
• Our 20th Anniversary Sale discounts apply only to in-stock special sale items ordered during the campaign period. Any order handling method is fine.
• Availability of 20th Anniversary Sale items' stock is subject to change without notice. An in-stock item in your cart may go out of stock if our last piece was ordered by another customer before you placed your order.
• Items with a stock status of "In Stock: Orders usually filled within (time frame)" are not eligible for sale discounts.
• Refunds or price adjustments are not available for any price differences for items purchased any time prior to or after that item's period as a sale item in the 20th Anniversary Sale.
• While supplies last, one randomly selected free gift will be included with every shipment of items during the sale period, from 12:00pm Thursday noon, Jun. 1, to 5:00pm Friday afternoon, Jun. 30, 2017 (all Japan Standard Time). Please be aware that the free gift is included at the time of shipment, and not at the time the order is placed.
• In the event of unforeseen circumstances, we reserve the right to end the campaign early.