Hey @Takeru.
This design is actually pretty easily to achieve with Cwicly, using div blocks instead of the menu block.
The menu block covers all basics in a pretty decent way but if you want to achieve something more advanced, it can get limitied - depending on what you have in mind.
Cwicly v1.3 (released 5 days ago) also introduced custom tags, such as <ul> and <li> which makes it now possible to create such submenus in a correct semantic way.
You can get some more info about potential improvements regarding the menu block here:
In case you have some specific things in mind, I think any opinion is appreciated to let the team know what users actually need.