The Takumi series brushes (apart from a couple of them) and a lot of Hakuhodo's J Series eye brushes (5522, 5523, 5529, 5533, 142, 146, various others) are made from the same hair type (Saikoho goat), I believe. I don't own any of the T series eye brushes, so I can't really speak to those, but I can link you to other reviews...
CHIKUHODO – Takumi Brushes – Sweet Makeup Temptations (Sonia owns a lot of Japanese brushes. Her Brush Temple was a valuable resource for me when I started researching Hakuhodo and Chikuhodo in particular.)
Chikuhodo Takumi Brush Set Review Review - Shameless Fripperies (Karima's another brush nerd
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That said, I own the T-4 and it is very soft. The main differences between it and the Z-4 (which I don't have but still want) are hair type (Saikoho goat for the T-4; grey squirrel for the Z-4) and price (Z-4 is more expensive). I think the shapes are somewhat different as well. The T-4 is a bit more pom-pom shaped.
Hakuhodo will offer you more in terms of shapes, which can be overwhelming. That said, it's a brand I would recommend to newbies to Japanese brushes, and then I'd rec starting with the J Series as it's the most affordable line Hakuhodo makes (there are a few face brushes that are over $100; the most expensive one is $115). The eye brushes in that range start in the teens and go into the $20 range.