I am a Japanese and am going to visit Frankfurt next week. My family asked me to buy Baumkuchen there but I couldn't find out where I can get it. Could you kindly give me advice where I can buy it?

Many bakeries carry this cake but not sure the best one to buy. This is the tree cake?

Thank you for your advice. It is the tree shaped cake.

I found the selection of Baumkuchen at Kyoto's central station quite amazing

In Germany, Baumkuchen originated in the Eastern parts of the country, in Dresden, for example, or Cottbus or Salzwedel, towns in the North East.
In other parts of the country, you may find some cafe-bakeries which make their own. But, in general, it's not such a huge thing that every cafe-bakery would have their own special Baumkuchen.

When searching the web, this was one Konditorei/cafe-bakery in the Frankfurt area:
Konditorei Hollhorst ?da schmeckt's wie in der guten alten Zeit!
It's on the Western edge, actually already in the town of Hofheim, so I don't know if it's worth the trek.

You should also find packaged "fit for travel" Baumkuchen in the food halls of large department stores in Frankfurt.

The (packaged/wrapped) Baumkuchen you find at any regular supermarket is not much different from the wrapped Baumkuchen you find at FamilyMart or Daily in Japan. And not worth taking home as a souvenir, IMO.

Happy travels!

Thank you for your feedbck. I arrived at Frankfurt and I went to a department store as you had recommended. There I found Baumkuchens and bought som for my family. I really appreciate it.