I emailed the hotel and got some more info:

We don’t have executive lounge in our hotel. We have lounge, but it is not complementally, we provide alcohol and food and sweet.

Platinum members benefit is below. You can choose one of them.

*500 points

*1000yen restaurant credit

*1 drink and appetizer

*Bottle of sparkling wine or red wine or premium juice

*cake set at the lounge

Breakfast is 3700JPY, but we offer 2000JPY for platinum elite member if you apply upon arrival.

Also if you choose 1000yen restaurant credit, you can eat breakfast with 1000JPY.

¥1,000 isn't bad, but a big reason I maintain platinum status is for a free breakfast for two (and lounge access). Here those benefits are watered down/non-existent.