Hiya
@mochill good to see you !
Well all I found so far was the stuff listed at their site, there are only 6 reviews so far but I will post ( used IMTranslator ) what makes a lot of sense from 2 of the reviews as far as their tuning.
I'll keep looking, as I do very much trust Kakaku.com reviews in Japan also ( hit 4th tab below listing for reviews of things )
" Perhaps because it uses the same voice coil as the HF1+, the dullness in the high range (8 to 10kHz or more) is reduced compared to the HF1 original, resulting in a solid tone, and the overall resolution has been improved.
...not a completely compatible model for the HF1 original. As someone who likes the neat and well-balanced sound of the HF1+, this was a much better impression on me, but
if you like the mild high range of the HF1 Muji, you might be a little disappointed. If you like low frequencies, don't worry. "
so a less mild highs , should sound like HF1+ highs but with lows like original model it seems.
and
" it was a perfection that exceeded trust.
The resolution is very high. As a result, even if each sound overlaps in a thick way, it won't get buried. In particular, the sexy vocals are irresistible. "
Kinda seems like an deal combo of both models?
I'll be trying them as soon as I can.
What I like about them is they are using all Japanese wire too.
( BTW slightly off topic ...have a peek at their upcoming fullsized washi paper driver headphone = blend of fine pulp and Mitsumata. )