I still say getting Tocchan as a bf is the easiest route.
He's legit in the Agency, the Market, Bookstore and Park. Yes, going on dates with him is kind of expensive if you're not using Shuu's cheat, which I did, to buy his preferred entire wardrobe, Regio (Elegant). On dates, touch his hand, pecs, and shoulder, do this enough times and in the ideal location, preferably a restaurant, or the bookstore, novel works best though you can give him the newspaper, also like the art gallery which has the most turns available, and he'll get heart eyes every date.
Based on my experience, going from Friends to Crush to Lovers happens in a pretty rapid pace depending on how often you see him during the week and go on dates. While using cheats, I've got to the Friends stage by early-mid March, on the 22nd, and Toru has just commented on how lovey-dovey MC and Tocchan look. This will soon lead to Crush, to get the best end, its important to wait til he confesses himself, and then Lovers~
Even when I didn't use cheats on my desktop, I'd say they were Lovers by late May.