the only way you can woo isabeau is to get the secret ending by getting Burroughs to admit she has a crush on Jonathan then get every demon on your team then you gotta get the chaos law and neutral endings [ at the same time] then and only then will you get to a room where theres a huge bed with isabeau on it wearing nothing but a corset stockings and heels she will say that you have come far but you have one last test then she summons GIGA MARA which is like regular mara but bigger vainer and blue and you have to fight GIGA MARA by yourself no demons and if you win THEN you will be worthy of whooing isabeau.
To woo Isabeau, you must go to a specific part of Naraku on the Neutral path and hit the wall with a spear 34 times. Upon the 34th strike, there will be a 1/9001 chance of the wall breaking. If the wall doesn't break you must repeat the process until it does. Once you enter the hole in the wall you will emerge in a kitchen where Isabeau will reveal that in order to woo her, you must defeat Merkabah and Lucifer in a 90-minute cooking contest. When you win, you feed your perfect dish to Isabeau, who transforms into Mara and fights you. After you defeat Mara Isabeau returns and congratulates the player as she and Flynn embrace each other... and the credits start rolling.
This is totally legit, my friend said his cousin who lives across the sea confirmed it. --- 3DS Friend Code: 3179-6117-3933 PSN: ansonip2000 Official Take-Mikazuchi of the Shin Megami Tensei IV board.