Your maple is not a seedling, it is a cutting and it's not Shishigashira.
Your maple is a cutting grown 'Koto Hime', and can be identified by the branching and bud character. Shishigashira does not have delicate buds and the branching is much more coarse than Koto Hime.
I have been propagating and growing Koto Hime Dwarf Japanese maple for over 40 years since I introduced it into the American bonsai community.
Attached are a few photos. The smaller bonsai is actually an air layer off the larger bonsai.
Also, by the way, your tree is not a seedling. Cultivars cannot be reproduced by seed, they can only be propagated asexually, vegetatively by cutting, graft, layer, division and tissue culture.
Enjoy your Koto Hime maple and try air layering it. It's easy to do and now is the time.
Bill