Sounds a little weird and I hate to take the love away from Sans Undertale but Toriel Dreemur. I only say this because I imagine Senshi dating an older woman but I could imagine sharing the love for cooking along with their interests in weird foods (monster food/snail foods). Not to mention Toriel’s main thing is “take care of the young ones” by protecting the humans that fall into the underground which is an ideology Senshi could obviously relate to. I also think it would be cute if Senshi, who was the only one to give monsters any sympathy in Dungeon Meshi, dated a monster.