The Kodomo No Omocha OVA is a thirty-minute animation video that was made before the TV series. It covers the first volume of the manga, so it's equivalent to TV episodes 1-6. It relates Sana's troubles with Hayama at school as a result of the "oyakodon baka" situation and culminates when Hayama's dad and sister realize their mistakes thanks to Sana's efforts.

As the sole survivor from a squad that was sacrificed and hung out as scapegoats for embezzlement of military resources at the end of the 100 years war, Mellowlink Arity is out for revenge. Carrying the dogtags of his deceased comrades and armed with a dated anti AT rifle, he swears to hunt down and exact revenge on the corrupt officers that betrayed his squad, and maybe even uncover the truth behind the plot as well.

The second part of the new Hokuto no Ken pentalogy. The story of this OVA centers around Yuria. (Source: Wikipedia)

On her first day of junior high school, Mato Kuroi meets Yomi Takanashi. Though Yomi is initially taken aback by Mako's straightforward personality, the pair quickly becomes friends and begin to spend time together daily. As a sign of their friendship, Mato gives Yomi a cell phone charm—a blue star, identical to her own. However, when the two enter their second year, their relationship starts to change. Placed in a different class, Mato begins to spend more time with Yuu Koutari instead, a girl she met through the basketball team. In fact, the former best friends drift apart so much so that Mato cannot find Yomi anywhere, as if she had disappeared entirely. Elsewhere, Black★Rock Shooter is on a quest to vanquish the Dead Master. These two, while opposed, bear a connection not unlike Mato and Yomi. As their stories begin to cross, it seems Yomi's disappearance may have to do with the blue star-shaped charm and the legendary gunslinger herself.