Successfully complete the game to unlock the "New Game+" option. Play your cleared game file to begin with all skills, money, friends, links, and some items from your first playthrough. Additionally, talk to one of the journey pigs in front of any town to access the Dragon Lair cave.
You can do training by hitting the wooden targets. Successfully complete the training mission by finishing all twenty rounds to unlock a weapon. The new weapon varies, depending on which weapon you are training with. Training with a sword will give you the Evil Sword. The spear will give you the Medusa Spear. The two-hand sword will give you the Grand Saber. The axe will give you the Icicle Axe. Also, when you do mission 19 for any of these, it will give 5,000 experience points. With two training devices, the experience is worth 8,000.
Remove the character(s) that you want to heal from your party and confirm. Then, put the character(s) back from the friend list into your party and they will be fully healed. Note: All status ailment (poison, blind, etc.) will be removed.
Successfully complete the Corridor Of Distortion dungeon to have Lenneth Valkyrie join your party.
Witness Tamaki Nami's transformation and immediately speak with her in the Night and Desire Street at 6:00 p.m. She will agree to join your party; however do not have her join your party, then visit the Red Lotus Bar at night. Tamaki Nami will sing the game's opening theme song.
Once in the bedroom and you have control of your character, you can kick the left desk to obtain ten coins. You can also kick the two beds to obtain additional items. Afterwards, leave the room, and kick the guard outside. You will receive one coin. You can do this for an unlimited amount of times. If you have a controller with an auto-fire feature, you can set it overnight to accumulate money easily.
Use the Arbitrator and do not use the sword you find in City Of White Nights. The best team consists of Gil, Serva, and Ganz (for non-human side). Aphelion regains HP, so you should be at least level 50 to 60 to take out more HP from him. He is very difficult. You should also have 30 to 45 Herb Extracts, 20 to 25 Herb Extract DS, 10 to 25 Herb Extract Max, 20 Sages, and 5 to 10 Celestial Nectars. Learn these command from books; use Volty, Circle and Life Song. Do not use any links. It may take 20 to 30 minutes to defeat him. You should also equip Samurai Armor (found at Goo's Armory if you are playing the non-human side at a cost of 60,000 Dagols) for a good defense. Always stay in the back of him -- his moves mostly attack from the front. Have your party to attack him mostly. If your life is low and it hits you, the game will end. When you get a full Volty gauge, use Limit Break.
This battle may only occur if you chose to follow Ridley rather than report to the castle, although this fight may be replaced with other characters. It is highly recommended that you have all the skills on your weapon. For example, use a non-elemental weapon like the Rune Sword, which is two-handed. The reason for this is that you will really want the second Volty attack in this battle, and the great thing about the Rune Sword is the ability to petrify enemies while attacking. First, prepare yourself with plenty of healing items. If you do not know where to go, head to the Dark Elf village via the Journey Pig. Have your Volty gauge set at 100 before the fight. If it is not, wander around and kill things. Also, if you are close to leveling up, do so. When you are prepared for the battle, go into the fort and go through the intermission sequence. The duo will attack you at the same time, but Natalie is very difficult. Concentrate all your power on her. Lock-on if you want to be sure not to direct attacks at Leonard. You can also try to petrify Leonard to worry less about your HP dropping. Unload your second Volty attack on Natalie the first chance you get. This will decrease her HP by about 70% to 80%. Then, just block and counterattack. Be careful not to hit more than once, because Natalie will most likely take out like another 180 to 220 HP or more from you while you are doing a combo. Then, just do counterattacks and Volty attacks every time you get 10 Voltys and she will go down fairly easy. You now only need to worry about Leonard, who has about the same amount of HP as Natalie but does not do close to as much damage. The purpose behind this is that Natalie has a Volty attack that does serious damage. It may even be a one-hit kill for a lot of characters. Make sure to use healing items or a heal command before the match ends.
Use the following trick to defeat Natalie and Leonard with a single handed sword. Depending on your level, this can be difficult due to Natalie's VoltyBlast attack. Have Cross Slash set as your primary attack, as you will not be doing many combos in this battle. Also, have your Volty Gauge close to 100 if possible. Concentrate all attacks on Natalie, as she is much stronger than Leonard. The best strategy is to guard, then counter after Natalie strikes. Do not start up a combo because she will hurt you badly. Continuing to block then counter to slowly drop Natalie's health to the point where you can use your VoltyBlast to take off about 250 to 300 HP, depending on your weapon and level. If you see flames coming out from around Natalie, get away from both of them and use whatever you have to heal to full life. Any commands that increase defense will also be helpful. Avoid getting hit until she either uses her VoltyBlast or some other command that uses the points. If you survived, heal and continue the strategy of block and counter. When Natalie is dead Leonard is not much of a threat. Use the same strategy to defeat him in a few minutes.
Once you are able to join the Fighter's Guild and you get Jack's Room in Radiata Town, notice a pair of red boots. They resemble the "Santa Boots" from the Star Ocean series.
Notice Gantz's appearance during events that feature him throughout the game. His outfit will begin to resemble that of Claude from Star Ocean 2 during the intermission sequences.
Once you are able to roam around the castle again after Ridley has joined the fairy creatures, go to her room. There will be a ghost on her bed. If you go to the ghost, you will wake up in your bed back under the bridge wearing Claude's uniform from Star Ocean: Till The End Of Time. It gives you HP regeneration.
Once you complete the game you have the opportunity to go through the Dragon Lair Cave. Once you finish that, you can go through the Corridor Of Distortion. Then, you will fight your father. After that, you will fight Lenneth Valkyrie, the main character of Valkyrie Profile. After you fight and recruit her, you will face an interesting character whose name is Lezard. This is Lezard Valeth from Valkyrie Profile. After that, you will face Gabriel Celeste, another hidden Boss from Valkyrie Profile. The final and toughest Boss, the Ethereal Queen, also seems to be modeled after Iseria Queen, also from Valkyrie Profile. Note: All of these characters, with the possible exception of Lezard, also appear in Star Ocean: Til The End Of Time.