I Was a Bit Shocked.

I requested a private High-Accuracy Parent-Child DNA Test (father-child).
I was told the results would be ready in 4 to 6 days, but after I shipped the sample (dropped it in the mailbox on the evening of 7/9)
I received an email 9 days later, on 7/18, saying "We will begin testing today."
It also stated that the results would only be available a further 5 to 7 business days after that.

If I count from 7/11, which is presumably when the sample actually arrived, as day 0, that comes to 8 to 10 business days —
double the number of days stated on the website and elsewhere.
Since it's summer, I was also worried about whether the sample would still be usable after all that time without degrading.
If it had degraded, wouldn't a retest from that point take yet another double the time?

My husband suspected me of infidelity, something there is absolutely no basis for, and I requested this test in order to prove him
completely wrong. I was looking forward to it, thinking "it's almost been 4 business days, so I should get the results by early next week at the latest,"
but then I received the notice above, and I was a bit shocked.

I think anyone in a hurry should definitely add the express testing option.

Thank you for applying for the High-Accuracy Parent-Child DNA Test and for sharing your feedback in your review.

We apologize that it took so long for your returned sample to reach us.
For every sample that arrives at our facility, we send an email the same day notifying you of the scheduled results date.
However, because Japan Post does not deliver regular mail on Saturdays, Sundays, or holidays, it typically takes 4 to 6 days (weekdays only) from the time you mail it until it reaches us.
Since a holiday fell within this period, delivery took longer than usual, and we will provide more detailed information about shipping times on our website going forward.

We also apologize for not explaining clearly enough regarding the number of days needed for results.
We count the day the sample arrives at our facility as "Day 0," with the following business day counted as Business Day 1.
(If the sample arrives in the afternoon, the following business day is counted as "Day 0.")
Accordingly, for a sample arriving on the morning of 7/18 (Thursday) or the afternoon of 7/17, 7/19 (Friday) is Business Day 1,
and since testing is suspended on Saturdays and Sundays, 7/22 (Monday) becomes Business Day 2.

As you pointed out, we do recommend the express testing option for customers who need their results quickly.
With our express testing option, the return envelope also becomes a "Letter Pack Light" for expedited delivery,
and the testing period itself is also shortened (to 2 to 3 business days), so please feel free to use this option according to your needs.