To make a long story short ... I visited a Suki-Ya restaurant (not this branch, but the one in Mont Kiara) with my meat-eating family.
The waiters confirmed that the soup did not contain any meat and should be suitable for vegans and vegetarians, but did not give me the impression that they had truly understood my question.
The next day I practically spent on the restroom ... leading me to doubt that the soup was 100% vegan or even vegetarian.
I guess when a waiter in Malaysia does not really understand what you are asking, he will respectfully agree with you to give you a good feeling. Speaking the local language will not help much, as most waiters are immigrants who have only a basic understanding of either English or the local language.
Same happens if you visit stalls selling Roti Chanai ... if you ask them whether it contains egg, in 99% of cases, they will decline and say, no, if you want to have egg, you need to order "Roti Telur" (Bread with egg).
Of course, the basic batter that they use for the Roti nevertheless is made with egg (and hence not suitable for vegans), unless you are in a vegetarian restaurant.
Cons: Serious doubts whether waiters understan, Serious doubt whether soup base is veg