Is this a Japanese Pagoda Tree?

[somewhatconcerned]

I have been growing this tree from seed for almost five months now. The packet it came in claimed the seeds inside were Sophora Japonica aka Japanese Pagoda Tree, however I just noticed that it has started growing thorns on the newer branches. I heard that they don't have any though. Can anyone try and ID it for me?

 

[Shibui]

Pretty sure the Sophora I once had did not have thorns.
The leaves on your seedling look like Pseudoacaia (Robinia / Black locust)which does have lots of thorns but it's still pretty young so difficult to be certain of ID

 

[somewhatconcerned]

Are those harder to care for? I have a black thumb and there were like twenty seedlings in the beginning, so only this one made it. I hope it doesn't die after so much time

 

[Attmos]

Are those harder to care for? I have a black thumb and there were like twenty seedlings in the beginning, so only this one made it. I hope it doesn't die after so much time

Personally, I'd love to have a Black Locust tree. I love the was they stand.

I've done a little reading on them and from what I understand, the thorns have been bred out of the species. I mean, you can still get them with thorns, but most of them used for landscaping and such are a cultivar that don't produce thorns.

Probly doesn't help AT ALL, lol, but I thought I'd mention it anyway.

 

[Betula1]

Black locust IMHO not particularly suited to bonsai, though Im sure someone here will prove me wrong! They can grow like weeds here and sucker like mad from the base and roots if cut back hard. The branches tend to be brittle and snap easily. There are some more attractive less thorny cultivars eg 'Casque Rouge' with beautiful pink flowers and 'Frisia' with golden leaves.

 

[somewhatconcerned]

Moral of the story, don't buy those "grown your own bonsai" kits off Amazon

 

[BonsaiManic]

I think I would agree with @Shibui, although ID is not my strength. It looks like black locust, which is native to 2 areas of the US. One is through most of the Ozark plateau, while the other range is a little further East from Pennsylvania down to Georgia by way of the Appalachians. I'm not sure where you are, but you can add that info to your profile to make it easier to give you more custom advice.
@Betula1, do you think honey locust is more suited to bonsai culture? I have one that will go in a basket in a couple of months.

 

[Shibui]

Both Black locust and honey locust have compound leaves. Not a definite no for bonsai but already makes it a bit harder to get nice compact growth.
Suckers are likely to be a pain. Olives are bad enough dealing with suckers but at least they develop flared base with small leaves and shorter internodes to make it easier to style a tree.

As mentioned, ID is not yet confirmed so keep growing and developing it for a few more years and see what you can do with it. Might still turn out to be something we haven't considered yet.