Alright, so I've been beating Mundus in Devil May Cry 1 for the past hour or two, so I'm just coming into this discussion.  

The reason Lien is a mission reward is because when I first created the missions section and started making missions, someone else was in the document at the same time.  While I was conceptualizing several missions, that person went ahead and made one, which was fine by me, and they included Lien as a reward.  I thought 'oh, that's something that's in the show, neat' and it became standard.  I never really had a purpose for it in mind.

I had always thought that players would use it of their own accord, in situations like the one provided, to pay for special things like a bicycle or a night of bowling and burgers.  If you want to work on an independent Lien shop, Sho, go ahead and make a page for it in the Conference Document.  Make sure to put WIP in the page header.  I'll take a look and let you know what I think.