Coming back to entry #173 (Sango no Umi to Ouji) and many similar releases...
While I was looking for information about some Toei Video releases, I ended up in a japanese blog that had two very interesting posts:
http://plaza.rakuten.co.jp/ikadaoriemon/diary/201002190000
http://plaza.rakuten.co.jp/ikadaoriemon/diary/201002270000
The first is an extensive list of all "V-Anime" VHS releases from Toei Video, which means all the more adult titles of their catalog.
The second is even more interesting, because it lists all anime where Toei Animation got a hand in the production, but that were not published by their video branch. Quite useful for the crazy collectors like me.
And actually it shows many items with "シナノ企画", that is Shinano Keikaku, the makers of entry #173.
If I extract these titles from the list, it goes like this (with VHS reference when found):
1/ 太平洋にかける虹 1992.03.20 (VA-8)
2/ シカとカンタ 1992.04.01
3/ ヒロシマへの旅 1994.07.20 (VA-10?)
4/ 二人の王子さま 1996.07.12 (VA-11)
5/ フィールドにそよぐ風 1997.07.25 (VA-12)
6/ ぼくたちのピース・リバー 1998.10.19 (VA-13)
7/ ヒマラヤの光の王国 1999.07 (VA-14)
8/ サンゴと海の王子 2000.02
9/ 大草原と白馬 2000.07
10/ さばくの国の王女さま 2001.03
11/ さばくの宝の城 2002.02
12/ アレクサンドロスの決断 2003.06
13/ 花と少年 2004.03
14/ あの山に登ろうよ 2005.03
15/ 輝け!友情のVサイン 2005.07
16/ 流れ星のおくりもの 2006.06 (VA-23)
And a separate entry, that was a series by itself:
人間革命 (全20巻) 1995.01-2004.11
Going back to Shinano Keikaku's webpage, one can make a correspondance with the recent DVD releases:
http://www.shinanokikaku.co.jp/?ac=user_product_list&gi=1&si=4
1/ AS-6 9/ AS-13
2/ AS-5 10/ AS-14
3/ AS-7 11/ AS-15
4/ AS-8 12/ AS-16
5/ AS-9 13/ AS-17
6/ AS-10 14/ AS-18
7/ AS-11 15/ AS-19
8/ AS-12 16/ AS-20
AS-1 少年とさくら
AS-2 お月さまと王女 (VA-5)
AS-3 青い海と少年
AS-4 雪国の王子さま
Titles AS-1 to AS-4 are older titles that were probably not produced by Toei Animation. All titles must be inspired by books of 池田 大作 (Ideka Daisaku), as his name (and face!) is everywhere. Now with one VHS reference it's clear that they come before.
About 人間革命, it's also there:
http://www.shinanokikaku.co.jp/?ac=user_product_list&gi=1&si=9
DVD contain two episodes. Must be semi-educational stuff, as
jfgslo already indicated.
To conclude from this giant puzzle, all of these are kids animation, probably sold apart from the usual anime market. This would be quite impossible to find any rips, unless you buy the DVDs.