@insert_name
Think of it like this.
He's already visited and conquered (in a way) most of the capital's brothels. Any fight he picks there if he wants to, is a guaranteed victory. And those brothels are probably home to some of the best in the nation.
Adding in mecha adds
1) MECHAS. A MAN'S DREAM.
2) The likelihood of him training and being stationed somewhere, which likely will either have different brothels or women who are into mecha pilots.
3) Mecha pilots are likely seen as elites, and they would probably have an easier time getting laid than standard infantry troops, meaning a whole new... section of female society becomes possible seduction targets with better success, compared to when he was just a potion-maker. I mean,let's not kid ourselves, pilots in our world have an easier time with women, right (might sound a bit misogynistic, but if you can prove me wrong, then feel free to do so)
4) If he does well enough, he's likely to get medals, rank or nobility. Thus opening up even further roads to being noticed, pursued and seduced by willing women. Not sure if nobility there have polygamy, but if he becomes one, there'll be lots of possibility for that.
That's atleast my thought. If it actually starts to focus a lot on mecha and skips all the 'fun' descriptions of his 'battles' so far, well, that's a bit sad. Might have to check the wn raws to be sure.