In the first four panels, only the ninja character should be dressed up in the cliché all-black ninja costume. Everyone else should be just regular people going about their lives.
Layout should be two panels in each of the first two rows and the final panel taking its own row.
1 - A baby dressed in a ninja costume is taking his first tentative steps. His mother stands before him, encouraging him to walk towards her, while his father is behind him, ready to provide support should a stumble appear.
2 - A few years later. That ninja baby is now a ninja teenager, replete with acne (visible through the open in his mask for his eyes), some type of braces / headgear (either above the mask for jokes or visible underneath), and possibly a letterman jacket or some such. He is sitting in a theatre with his date, casting furtive glances towards her out of the corner of his eye. Maybe he's visibly working up the nerve to make his move.
3 - A few more years later. That ninja teenager is now a ninja man. It is his wedding day. Still in full ninja garb, he now also wears a tuxedo overtop of it all as he stands next to his beautiful bride (who is obviously the same girl from the movie theatre). They're at the part where they get to kiss. It is obviously the happiest day of their lives, and everyone watching on is pretty pleased about the whole thing too (and all wearing regular, non-ninja garb, natch).
4 - A few more years yet. That ninja man is now a slightly older ninja man. We're in the driveway in front of his and his wife's house. He stands at the doorway, waving goodbye as he heads off to work. She's also pregnant (because, obviously she is). I'd say to have the ninja wearing a suit over his ninja garb, but that might be too much, so let's just say he's holding a suitcase as he unlock his car to drive to work.
5 - The present. There's a big ol' fight going down. A group of ninja is getting their collective tail handed to them by a few colourful superhero-esque mercenaries. Our focus, however is on two colourful heroes who are looking down at a fallen ninja. The first hero cleans off his sword, the second holds her two guns at her side. The first hero asks a question to which the second shrugs her shoulders as if to say "I dunno".
FIRST HERO: You think anything flashes before a ninja's eyes when they die?