Now that you have Jinn, walk out of the Corridor of Wind (or use an Escape Rope if you want). Then head back to the flower garden. The Elder of Rolante will be waiting for you there. Use Jinn to blow the sleep flowers to the castle and then you will be transported to the castle gates.
There are two barrels full of items in there. One has 9 Round Drops in it and then other has 3 Angel Grails. Unfortunately, if you don't have room for all of them in your item ring, they will just give you enough to get 9 in your item ring. So to get the most out of these barrels, put all your Round Drops into storage (and all your Angel Grails if you have more than 6) before opening them.
The castle is big, but fortunately rather linear once you get on the right path. Go in through the gate, and go through the small door to the northeast of the main door (or if you want to heal and save first, go southeast of the little door and use the golden statue in the room there). Go into the door and fight the ninjas there. Then go through the door in the northeast corner of that room. The rest of it is linear. When you get on the balcony the first time, the door to the next screen is somewhat hidden; go as far north as you can on that screen and then walk right to find it.
Continue on. In the second room with the three Evil Swords, there are two exits. One leads outside, to a balcony. The other leads to a Gold Statue (make sure you use it!). When you reach the balcony, Lise will be there if she's not in your party. The enemy general is inside the door behind her. Don't go in yet. Pull up the item storage menu, and get out your Ice Coins and Poseidon's Claws; also pull all the Round Drops, Pakkun Chocolates, and Angel Grails that you can out of storage. If you have Kevin, make sure it's night. The next section requires you to fight two bosses in a row. When you're ready, go through the door and fight the first one.
No relation to Jenova. The strategy here is fairly simple. Genova is Fire-based, and knows a good amount of Salamando's magic, including Power Up, Fireball, and Melt Wave. Genova is only level 10, but can also spit out level 10 Shapeshifters. These little dudes are annoying for two reasons: One, they can shapeshift, and every time they do, they regain health; two, they have the attack strength and elemental attributes of whatever they Shift into. This means that they can become level 10 Devil Wolfs, with very strong attack; they can also become level 10 Sirens that absorb Wind Magic. Anyway, use the Poseidon's Claws on yourselves and use up all of your Ice Coins on Genova. Focus your attacks on Genova itself and try to let your partners take care of the Shapeshifters. You will need to keep your HP at least over 90, as Genova knows level 1 and level 2 Trap Magic.
You will get a heal after you beat Genova, but you can't leave. You can only go forward. Before doing so, pull up the storage menu. You should store any leftover coins you have. If you have anything throwable that hurts one enemy, like Darts, Axes, Bombs, or Assassin Bug Eyes, bring it. Also, bring any leftover Claws, and fill back up on Angel Grails, Pakkun Chocolates, and Round Drops. Go into the next room.
Boss: Bill and Ben
Bill and Ben are very annoying. They are essentially level 12 Ninja Masters, one of Hawk's final Classes (dark-light, in case your were wondering), and they are hard, especially right after a boss fight. One of the things that makes them annoying is that they can cast spells and techs very quickly. At the beginning, they will fuse. This is your time to hit them with all the one-enemy items. After they separate, do not use any Magic or Magic-casting items on them, because they will counter with Shadow Dive or a Jutsu. Actually, they'll use Shadow Dive on you no matter what, so be prepared and keep HP very high. You can try Specter Eyes to cancel their Techs. They are not weak to any one Saber, but if you Saber yourselves, you can increase the amount of damage you do to them. If they hit you with a Jutsu, you can return your stats to normal with a Stardust Herb if you want, but that will also remove your Saber effect if you have one. Persevere and eventually they will die. If you lack Kevin or Duran, this can be a very long fight. However, if you have two or three powerful fighters in your group, you may be surprised at how quickly they go down.
When you're finished, chat with Bigieu. She doesn't look pleased. She'll run off, and the castle of Rolante is free again!