Just Bento

Hmm...I am not sure what you mean (or what your friend means). Some things are called 'tofu' but do not actually contain soy at all, including some desserts, like an-nin-dofu which is actually almond milk gellified with agar-agar. Also, if it's a Vietnamese ingredient, it may not be that readily available in Japan...which doesn't have a big Vietnamese expat population. Maybe you can ask her to clarify what she means.

there are kits that make tofu one is made by a house I think its called hon tofu mix

Yes there is House Hon-dofu mix, but it doesn't quite sound like what Supertaster's friend is looking for to me... it isn't a dessert ingredient in any way. I am just guessing that the Vietnamese dessert is closer to the almond "tofu" I mentioned, maybe made with coconut milk or something (but I'm just guessing here).

The Vietnamese dessert you are referring to is is made with agar-agar and flavored with various ingredients. Different flavors are often layered together in molds. Green layers are flavored with pandan leaf extract. Brown layers are mocha or caramel flavored. White layers (which resemble tofu) are made with coconut milk. When feeding a lot of guests, it is usually made into large, layered sheets that are cut into pieces.

Here is an example (in Vietnamese) using just coconut milk and mocha flavors:
http://beplolem.blogspot.com/2009/06/ong-suong-thach.html
Instead of making clearly defined layers, she swirls them together for a marbleized effect.

Thank you so much for everyone's help. I'm still waiting to hear from my friend exactly what she's referring to, but Arigomi's link looks promising. I'll let you know when I know. Thanks!