Tanabata-tsume, the Weaver Maid, is the patron deity of weaving in Japan and the subject of an old and beautiful legend. Devoted to her husband, she neglected her work, and was banished across the River of Heaven (the Milky Way). However, once a year, birds form a bridge over the river with their wings so the couple can be reunited for one night - the night when women pray for skill in Japan's marvelous textile traditions.
Tanabata is on July 7th and is a part of Japanese folklore. The day celebrates the legend of Orihime and Hikoboshi (associated with the stars Vega and Altair), two deities that were separated by an entire galaxy for being too in love to do their jobs. Additionally, the Milky Way (Amanogawa) is considered a literal river.
A couple scorned by the Gods, separated by the Milky Way itself. Only once a year, on the night of Tanabata, were they permitted to meet. But even then, only if the sky was clear. And with the threat of overcast skies, such an occasion was rare indeed. People came to call the Tanabata rain a rain of tears.
星のとなりの空け者 ～織姫～ (Hoshi no Tonari no Utsukemono ~Orihime~)
Sung from the character Orihime's perspective, which corresponds with the star Vega. This song is considered to be the first of the series, despite Manbou saying they could be watched in any order. The song starts with the "prologue" of the series, and then continues on to Orihime's song.
Orihime, sad that the "promised day" has never been clear, she searched for a loophole in the god's trick and finds that Kappa could cross the Milky Way. The only problem is they're an extremely rare youkai. One day, when she was walking on the outskirts of town, she found a crowd of youkai. She was surprised and a little put-off to find they were all crying. Their shoelaces were untied because their mothers always did it for them. "Feeling pity for the imbeciles," she taught them to tie their shoes. The amazed and overjoyed demons then decided that they'd follow her anywhere.
Orihime ended up forming a "fearsome youkai dispatch company." The idiotic youkai were payed low wages "but given packs of gum, they worked with glee." The business blossomed and they even got along with politicians. Orihime ended up forgetting about the possibility of crossing the river and devoted herself to the important management of the company.
Hearing the reputation of this idiotic company with youkai too stupid to figure out the process of meal tickets, a kappa decided to come in for an interview. Orihime has a strange feeling that she's been looking for a kappa when suddenly the PV shows a flashback of her meeting Hikoboshi when she was younger and how they ended up close before being separated.
Finally, on the night of Tanabata, Orihime admits she ignored the pain of not meeting him, often pretending to just be deep in thought. She begs the kappa, with tears in her eyes, to bring Hikoboshi to her. The kappa agreed and flew over the river, where it suddenly started beating up Hikoboshi. Orihime is surprised and confused, stating that the youkai are all as dumb as each other; "So slow returning, but such a fast puncher!"
The song ends with Hikoboshi looking "more mature than he'd been before," and a "to be continued" sign.
星のとなりの空け者～彦星～ (Hoshi no Tonari no Utsukemono ~Hikoboshi~)
Sung from the viewpoint of the character named Hikoboshi, corresponding with the star Altair. It is considered to be the second song of the series, despite Manbou stating they could be watched in any order. The song starts with the "prologue" of the series, and then continues to Hikoboshi's song.
The song begins with Hikoboshi and an ox as he rants on how "this night's never been clear" and he's sure that, night after night, it'll always rain. The only ones known to be able to cross the river were a rare youkai called Kappa. Hikoboshi then ponders if it's something they possess. He comes to the conclusion that all he needs is their might and lung capacity.
It then moves on to another him surround by pills (presumably steroids or something similar) as he lifts oxen by their horns. Hikoboshi admits 60% of his wages now go to his muscles. He then repeats the same line Orihime had in her song, "Isn't crossing the Milky Way just science fiction?" yet his obsession is with exercise rather than business.
星のとなりの空け者 〜カッパ〜 (Hoshi no Tonari no Utsukemono ~Kappa~)
Sung from the view of a Kappa, a rare youkai that can cross the Milky Way river. It is considered to be the third and final of the series despite Manbou saying that they could be watched in any order. This song sums up all events and viewpoints, and reveals the series' moral.
In this song, the Kappa mentioned itself that even though it knew about the tale of the separated couple, all it wanted was a job, since it got rejected many times. Hearing about the idiotic company of Orihime, it came for an interview, and met her.
Orihime soon requested it to bring Hikoboshi to her. The Kappa didn't want to do it, but it did for the job. It came to the other bank to find "a man with musculus muscles (who was Hikoboshi)," and was attacked by him. The man stated that if he won a fight against a Kappa, he could cross the river. The Kappa, however, made him keel over and dragged him back to Orihime. It's now said that surely the couple didn't know that two river banks had different time flows.
When the Kappa returned, Orihime was aged, but Hikoboshi was still young. The Kappa felt bad for the couple ending up like that. However, before it could say anything, the two lovers were simply joyous and happy, something which brought tears to the Kappa's eyes. It wondered how, after being divided for so long and then having an awful reunion, they could be so joyous. Orihime and Hikoboshi replied "Because we love each other..." which is the moral of the series.