This kata is called 'Storming the Fortress', and this is evident from the power and strength that is demonstrated in the kata. Its name was changed to Bassai Dai by Gichin Funakoshi. Its origins are from pre-1869 Kosaku Matsumora, Tomari-te style.
Note: Because of its overwhelming use in Wado techniques, if only one hand is mentioned, the other hand is performing a back hikite. Also, unless otherwise mentioned, all jun-tsukis are at the chudan (solar plexus) level.
Rei. Masuba dachi.
Yoi. Gedan sasae uke. Heisoku dachi.
Hajime.
Step forward left shooto supporting right soto uke. Right gyaku neeko ashi dachi.
Left leg goes back, then mawata left, 180°, into right ude uke, left soto uke. Left seisan dachi.
Right leg goes back, then mawata right, 180°, into left ude uke, right soto uke. Right seisan dachi.
Mawata right, 90°, with right counterclockwise ude uke, left soto uke. Right neeko ashi dachi.
Mawata left, 90°, left tae uke. Heiko dachi.
Left gedan uke, right chudan jun-tsuki. Heiko dachi.
Drop into right soto uke. Left naname zenkutsa dachi.
Pull up left chudan jun-tsuki. Heiko dachi.
Drop into left soto uke. Right naname zenkutsa dachi.
Pull left in, then go forward with right soto shooto uke, left chudan shooto uke. Right mahanmi no neeko ashi dachi.
Press down the right soto uke, cover face with left chudan uke, slide forward and hit opposite stance and hit right chudan shooto uke, and left soto shooto uke. Left mahanmi no neeko ashi dachi.
Press down the soto uke, slide forward into right soto shooto uke, left chudan soto uke. Right mahanmi no neeko ashi dachi.
Yoi hidari nodo tsukami, migi kinteki shotei uke. (pull back left throat grab, right palmheel groin block). Left mahanmi no neeko ashi dachi.
Mawata left 180°, double gedan sukami to attacker’s kick, then counter with hiza yoko geri as you pull hands in. Kosa dachi (crossed stance), kick, drop into left mahanmi no neeko ashi dachi.
Face left, left soto shooto uke, right chudan shooto uke. Left mahanmi no neeko ashi dachi.
Press down the soto uke, slide forward into right soto shooto uke, left chudan shooto uke. Right mahanmi no neeko ashi dachi.
Pull back into double gedan kinteki seikan ukes, thumb sides touching. Age seikans, to forehead, rotating so that at apex, the knuckles are touching. Heisoku dachi.
Step forward into double chudan ura tsukis. Right zenkutsa dachi.
Slip forward again, into right chudan jun-tsuki. Slip up, right zenkutsa dachi.
Mawata left, 90°, into a left jodan tetsui, right soto uke. Heiko dachi.
Mawata left, 180°, into a right gedan tetsui. Sheeko dachi.
Face left and pull up into left gedan tetsui. Heiko dachi.
Mawata left, 180°, right age (rising) heisoku geri into a left hirate, then continue hirate into right empi, followed by a right gedan uke, left chudan uke. Sheeko dachi.
Switch hands to left gedan uke/right chudan uke with palm down, and then back to right gedan uke/left chudan uke with palm up. Sheeko dachi.
Pull in left, hands to obi, right tomoe tsuki. Right seisan dachi.
Pull back into left tae uke, then right tomoe tsuki. Left seisan dachi.
Pull back into right tae uke, then left tomoe tsuki. Right seisan dachi.
Left mawata (180°), right soto uke. Left naname zenkutsa dachi.
Left soto uke. Right naname zenkutsa dachi.
Pull in left foot to masuba dachi, then right shooto soto uke, left chudan shooto uke. Right mahanmi no neeko ashi dachi.
Mawata hips right 135° to back right corner, slowly bringing hands to a back angle right shooto soto uke, left chudan shooto uke, while facing front left corner. Right mahanmi no neeko ashi dachi.
Slip forward towards left front angle, hips and legs first, then slowly into a left soto shooto uke, right chudan shooto uke. Left mahanmi no neeko ashi dachi.
Yame. Pull back hidari, and up migi into gedan sasae uke, heisoku dachi.
Norei. Masuba dachi.
Rei.