Bemstar was an energy absorbing monster from the Crab Nebula, a supernova remnant and nebula in the constellation of Taurus. He came into the solar system looking for cosmic energy, eating a highly developed space station monitored by MAT. Bemstar soon landed on Earth, attacking a nearby city where MAT counterattacked. Ultraman Jack arrived to do battle, but the beam absorbing alien withstood against most of Jack's attacks, even absorbing the Spacium Beam into his gorge.

Jack became extremely weak using up most of his attacks on Bemstar, so in an attempt to recover his energy, he flew directly towards the Sun! However, as Jack neared the star, Jack absorbed too much energy, and the star's incredibly powerful gravitational field overwhelmed him, leaving the Ultra at the Sun's mercy. Just before Jack could hurtle uncontrollably into the Sun's atmosphere towards certain death, Ultraseven arrived just in time to save Jack. After a brief discussion, Seven gave Jack the Ultra Bracelet, a shape shifting weapon that Jack wore on his wrist. Jack, now rejuvenated from the Sun and armed with the new weapon, returned to Earth and fought Bemstar again, this time with greater enthusiasm.