just answered your own question 

i dont see how an Asa route would be any diffrent from the normal "older woman" or "sensei" route in other adult game... she looks incredibly young for a mother.... and if shes not well.... its not like shes not legal like some of the other chracters apear....

Her age is never stated, but everyone makes jokes that they want to know her secret for eternal youth. It could be an aftereffect of the experiment done on her, but they never develop it any further.

a perfect excuse as any to make a route for her

Yuria won't moan for the audience, so you'll never have an Ama route.

EDIT: A-M-A!

well that just sucks

Damned Yuria!

Lol thanks for fixing my mistake Mana

No problem! It happens a lot of times when talking about them, but I thought it would be funnier just to edit your post.

Ama herself isn't quite the problem... it's the fact she's Asa's mom that really gets to me O.O ... since the anime, Asa's route has always been most memorable for me... the double personality of the other two confuses me if I review the game, lol... but going after Asa's mom seems like appropriate territory O.O... your sempai's single mom should be off limits since the main would make a fail dad.

Hey going after Nerine's mom and even opening the package before Nerine's dad did is A-OK! but don't even think about laying a finger on Ama lol. Sage is so cute!

You can go after Nerine's mom (Sage) in Tick Tack.

lol, totally forgot about that

Now that... is time travel in action. rofl.

I know what's his problem, he doesn't like used goods. That's why he is fine with Tick! Tack!.

OBJECTION! whos to say he isent Asa's farther..... think terminator...