I grew some dark seed of 'Sazanami' (#1) from Ronnie. Can't recall , if they were quite that yellow. But, I sprout mine in baggy with moist coffee filter, first. Then pot up & place in some direct sun & shade. Those are now normal green, ( may have started out, pale?) with with darker red stems, now. While a packet, as "Ukigumo" the seed was (rather old ) & 'entirely pale seeds. Yet 'Sazanami' was on the other packet, with one pale seed & all other seedlings stems are dark in color, now.
What the slugs didn't finish in the way of the seedling stems, are now still green, but just planted a seedling again, from this so called "Ukigumo" packet & have two, now.
I only got the one, which seems to stay small, possibly (#2) 'Sazanami',as the description on packet stated, as though it may resemble 'Sazanami #2, ( instead of 'Ukigumo' which was what it was labelled as) & the name written on the "trade packet.". Likely from a co-op, some years ago.
It will be nice to see how they all turn out, & won't know for certain, until they do flower. These were variegated/ pale cotyledons. & a couple are green stemmed & the others dark stems now.Tiny, first leaves so far & slow growing...
Except, I trust the packet of 'Sazanami' from Ronnie, is as what it should be.