Volcano crater in march/april

We are real vulcano fans and would like to know if it is possible to see any of the crater lakes in the next month. We will be in Japan end of march/ first days of april. It is not possible to see the Mount Aso crater lake because of the activity of the vulcano. Seems like it is also to early to see Mount Zao. Are there other options at this time?
Is it worth travelling to Mount Aso these days when you cant go near the crater? What are the options to do there now? Is it possible to go for hiking?
Thank you very much for your help!

This ia volcano lakes list from north(Hokkaido).
http://ichiranya.com/technology/015-volcanic_lake.php
Use google translate,image search and map.

Zao closing right by heavy snow still covered until GW(late Apr).
Aso[ˆ¢‘h] is still warning level[Œx•ñ/Œx‰ú] 2[ƒŒƒxƒ‹ 2] today.
http://www.data.jma.go.jp/svd/vois/data/tokyo/STOCK/kaisetsu/level_toh...
http://www.data.jma.go.jp/svd/vois/data/tokyo/keikailevel.html
Latest pic of this month yet but seems very active no safe.
http://www.jma-net.go.jp/aso/nakadake/kansoku.html
http://rkk.jp/livecamera/aso_live.php [live cam]

Hey, thank you very much! Looks like there are no options. :-( Maybe we will got Mt Aso one day and see it from little far. Do you know if people can still gofor trekking in the park or is the whole area around it closed? But I read that it is only one km which you hve to stay far from the crater.
Again, thank you for your links!