Bought the 30 day 20gb Japan eSIM and it worked perfectly.

I purchased the "Unlimited" 30-day plan, It turned out to be misleading. Once I exceeded 1GB of data usage in a day, the speed throttled down to 250-500Kbps.
There isn't any clear mention of this limit.

The latency remains relatively low since the internet breakout is located in Singapore.

~1GB per day at full speed for 50EUR is very expensive, I wouldn't recommend this plan.

The purchase/installation was straightforward.

Very slow even with excellent signal strength (4G, iPhone XS), unusable even for maps and messaging. Very high ping times (600ms+). Support is very slow as well and did not fix the issue nor provide a refund.

Works great! Good coverage (docomo network it seems), Japanese IP, and good ping times to Europe. Used with an iPhone XS on LTE. Attached Speedtest is from a train

Extremely poor support that doesn’t respond to any help after 24 hours.

Paid and activated the sim but couldn’t get any internet connection (despite successfully connected to SoftBank 3G).

I’ve checked many times that apn and roaming is enabled. And re started my phone multiple times.

Issue was never resolved and Airalo support was non existent.