Arima-san wa Omega ni Naritai 2nd Season

Izumi and Arima are now happily settled down with their son, Ayumu, but Arima dearly wants to grow their family. His unusual physical constitution makes this difficult, so when Izumi's obstetrician brother mentions an experimental drug he's developing to induce heats, Arima jumps at the chance to increase his chances of giving Izumi a second child. Reluctant but ever-supportive Izumi agrees to his plan, but is it really such a good idea?