>>60203634I second most of the replies, but I'd also like to throw Azki out there since Suisei admires her, which could make for an interesting dynamic. You could also flip it and make the love rival Iroha, which would force Iroha into choosing her oshi's happiness or her happiness, though this would make it more centered around Iroha than Suisei. Aqua would be fun as well since Suisei thinks she's adorable and innocent, so it would be hilarious when she finds out she's in danger of getting cucked by the onion.
>>60205766God imagine Suisei seeing Anon be drawn to Hoshikawa's busty body and feeling cornered, thus forcing her to try and break out her womanly charms in order to win him over, despite being flat as fuck and hating it. That would be so hot.