Tsubame Arrives (Tsubame The Ninja Girl) (Hattori has a Guest) (ツバメ殿は手強い女忍者でござるの巻) is episode 172 of the Ninja Hattori-kun 1981 anime.
Kenichi is shocked when somebody breaks into the house and binds and gags him. Don't worry, she's not a burglar - she's Tsubame, Hattori's childhood sweetheart. But Tsubame is no match for Kenichi, Shinzo and Shishimaru.
Kenichi returns home after practising baseball - when he finds the house keys perched on top of the wall. Standing on tiptoe, he gets the keys, and then he unlocks the door. He then finds out that someone has broken in, and then he hears a shrill singing voice, and then he sees a girl - who, most unfortunately, is NOT Yumeko Kawai. The girl then throws her soap and recorder at him and immobilises him. Shinzo and Shishimaru return home, and then a shaken Kenichi tells them about what happened. They then go upstairs and try to find the girl and immobilise her - but then they are attacked. Hattori then returns home with Mrs Mitsuba after some shopping - but the girl then drops her violent side and greets Hattori shrilly.
Hattori then introduces her to Kenichi, Shinzo and Shishimaru - she is Tsubame, a girl from Iga town who is infatuated with him. She then reveals that she bought robes for Hattori as a gift - but nothing for the others! She then offers to wash his clothes (how embarrassing) and then cooks food for Hattori and only Hattori (how biassed) and then offers to sleep with him and Shinzo in the attic (how revolting)!
Next morning, at about six o'clock, Tsubame then cleans the house for the Mitsubas, who all turn up in the living room yawning and stretching - all except Kenichi. She then goes to wake him up and despite Mrs Mitsuba saying that Kenichi usually sleeps in at weekends, she uses an advanced piece of ninja - ism (where we get to see her knickers) and throws Kenichi off his bed (ouch)! Hattori then tells the viewers to beware of ninjas.